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* sched: recover SD_WAKE_AFFINE in select_task_rq_fair and code clean upAlex Shi2012-08-13
| | | | | | | | | | | | | | Since power saving code was removed from sched now, the implement code is out of service in this function, and even pollute other logical. like, 'want_sd' never has chance to be set '0', that remove the effect of SD_WAKE_AFFINE here. So, clean up the obsolete code, includes SD_PREFER_LOCAL. Signed-off-by: Alex Shi <alex.shi@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/5028F431.6000306@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* sched/numa: Add SD_PERFER_SIBLING to CPU domainAlex Shi2012-07-26
| | | | | | | | | | | | | | | | | | | | | Commit 8e7fbcbc22c ("sched: Remove stale power aware scheduling remnants and dysfunctional knobs") removed SD_PERFER_SIBLING from the CPU domain. On NUMA machines this causes that load_balance() doesn't perfer LCPU in same physical CPU package. It causes some actual performance regressions on our NUMA machines from Core2 to NHM and SNB. Adding this domain flag again recovers the performance drop. This change doesn't have any bad impact on any of my benchmarks: specjbb, kbuild, fio, hackbench .. etc, on all my machines. Signed-off-by: Alex Shi <alex.shi@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1342765190-21540-1-git-send-email-alex.shi@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2012-05-22
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler changes from Ingo Molnar: "The biggest change is the cleanup/simplification of the load-balancer: instead of the current practice of architectures twiddling scheduler internal data structures and providing the scheduler domains in colorfully inconsistent ways, we now have generic scheduler code in kernel/sched/core.c:sched_init_numa() that looks at the architecture's node_distance() parameters and (while not fully trusting it) deducts a NUMA topology from it. This inevitably changes balancing behavior - hopefully for the better. There are various smaller optimizations, cleanups and fixlets as well" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Taint kernel with TAINT_WARN after sleep-in-atomic bug sched: Remove stale power aware scheduling remnants and dysfunctional knobs sched/debug: Fix printing large integers on 32-bit platforms sched/fair: Improve the ->group_imb logic sched/nohz: Fix rq->cpu_load[] calculations sched/numa: Don't scale the imbalance sched/fair: Revert sched-domain iteration breakage sched/x86: Rewrite set_cpu_sibling_map() sched/numa: Fix the new NUMA topology bits sched/numa: Rewrite the CONFIG_NUMA sched domain support sched/fair: Propagate 'struct lb_env' usage into find_busiest_group sched/fair: Add some serialization to the sched_domain load-balance walk sched/fair: Let minimally loaded cpu balance the group sched: Change rq->nr_running to unsigned int x86/numa: Check for nonsensical topologies on real hw as well x86/numa: Hard partition cpu topology masks on node boundaries x86/numa: Allow specifying node_distance() for numa=fake x86/sched: Make mwait_usable() heed to "idle=" kernel parameters properly sched: Update documentation and comments sched_rt: Avoid unnecessary dequeue and enqueue of pushable tasks in set_cpus_allowed_rt()
| * sched: Remove stale power aware scheduling remnants and dysfunctional knobsPeter Zijlstra2012-05-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's been broken forever (i.e. it's not scheduling in a power aware fashion), as reported by Suresh and others sending patches, and nobody cares enough to fix it properly ... so remove it to make space free for something better. There's various problems with the code as it stands today, first and foremost the user interface which is bound to topology levels and has multiple values per level. This results in a state explosion which the administrator or distro needs to master and almost nobody does. Furthermore large configuration state spaces aren't good, it means the thing doesn't just work right because it's either under so many impossibe to meet constraints, or even if there's an achievable state workloads have to be aware of it precisely and can never meet it for dynamic workloads. So pushing this kind of decision to user-space was a bad idea even with a single knob - it's exponentially worse with knobs on every node of the topology. There is a proposal to replace the user interface with a single 3 state knob: sched_balance_policy := { performance, power, auto } where 'auto' would be the preferred default which looks at things like Battery/AC mode and possible cpufreq state or whatever the hw exposes to show us power use expectations - but there's been no progress on it in the past many months. Aside from that, the actual implementation of the various knobs is known to be broken. There have been sporadic attempts at fixing things but these always stop short of reaching a mergable state. Therefore this wholesale removal with the hopes of spurring people who care to come forward once again and work on a coherent replacement. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * sched/numa: Rewrite the CONFIG_NUMA sched domain supportPeter Zijlstra2012-05-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current code groups up to 16 nodes in a level and then puts an ALLNODES domain spanning the entire tree on top of that. This doesn't reflect the numa topology and esp for the smaller not-fully-connected machines out there today this might make a difference. Therefore, build a proper numa topology based on node_distance(). Since there's no fixed numa layers anymore, the static SD_NODE_INIT and SD_ALLNODES_INIT aren't usable anymore, the new code tries to construct something similar and scales some values either on the number of cpus in the domain and/or the node_distance() ratio. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Anton Blanchard <anton@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: linux-alpha@vger.kernel.org Cc: linux-ia64@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-sh@vger.kernel.org Cc: Matt Turner <mattst88@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: sparclinux@vger.kernel.org Cc: Tony Luck <tony.luck@intel.com> Cc: x86@kernel.org Cc: Dimitri Sivanich <sivanich@sgi.com> Cc: Greg Pearson <greg.pearson@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: bob.picco@oracle.com Cc: chris.mason@oracle.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-r74n3n8hhuc2ynbrnp3vt954@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | x86: replace percpu_xxx funcs with this_cpu_xxxAlex Shi2012-05-14
|/ | | | | | | | | | | | | | | | | | | | | | | | | | Since percpu_xxx() serial functions are duplicated with this_cpu_xxx(). Removing percpu_xxx() definition and replacing them by this_cpu_xxx() in code. There is no function change in this patch, just preparation for later percpu_xxx serial function removing. On x86 machine the this_cpu_xxx() serial functions are same as __this_cpu_xxx() without no unnecessary premmpt enable/disable. Thanks for Stephen Rothwell, he found and fixed a i386 build error in the patch. Also thanks for Andrew Morton, he kept updating the patchset in Linus' tree. Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Tejun Heo <tj@kernel.org>
* sched: Allow SD_NODES_PER_DOMAIN to be overriddenAnton Blanchard2011-09-20
| | | | | | | | | We want to override the default value of SD_NODES_PER_DOMAIN on ppc64, so move it into linux/topology.h. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* mm: increase RECLAIM_DISTANCE to 30KOSAKI Motohiro2011-06-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recently, Robert Mueller reported (http://lkml.org/lkml/2010/9/12/236) that zone_reclaim_mode doesn't work properly on his new NUMA server (Dual Xeon E5520 + Intel S5520UR MB). He is using Cyrus IMAPd and it's built on a very traditional single-process model. * a master process which reads config files and manages the other process * multiple imapd processes, one per connection * multiple pop3d processes, one per connection * multiple lmtpd processes, one per connection * periodical "cleanup" processes. There are thousands of independent processes. The problem is, recent Intel motherboard turn on zone_reclaim_mode by default and traditional prefork model software don't work well on it. Unfortunatelly, such models are still typical even in the 21st century. We can't ignore them. This patch raises the zone_reclaim_mode threshold to 30. 30 doesn't have any specific meaning. but 20 means that one-hop QPI/Hypertransport and such relatively cheap 2-4 socket machine are often used for traditional servers as above. The intention is that these machines don't use zone_reclaim_mode. Note: ia64 and Power have arch specific RECLAIM_DISTANCE definitions. This patch doesn't change such high-end NUMA machine behavior. Dave Hansen said: : I know specifically of pieces of x86 hardware that set the information : in the BIOS to '21' *specifically* so they'll get the zone_reclaim_mode : behavior which that implies. : : They've done performance testing and run very large and scary benchmarks : to make sure that they _want_ this turned on. What this means for them : is that they'll probably be de-optimized, at least on newer versions of : the kernel. : : If you want to do this for particular systems, maybe _that_'s what we : should do. Have a list of specific configurations that need the : defaults overridden either because they're buggy, or they have an : unusual hardware configuration not really reflected in the distance : table. And later said: : The original change in the hardware tables was for the benefit of a : benchmark. Said benchmark isn't going to get run on mainline until the : next batch of enterprise distros drops, at which point the hardware where : this was done will be irrelevant for the benchmark. I'm sure any new : hardware will just set this distance to another yet arbitrary value to : make the kernel do what it wants. :) : : Also, when the hardware got _set_ to this initially, I complained. So, I : guess I'm getting my way now, with this patch. I'm cool with it. Reported-by: Robert Mueller <robm@fastmail.fm> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: "Luck, Tony" <tony.luck@intel.com> Acked-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: Add book scheduling domainHeiko Carstens2010-09-09
| | | | | | | | | | | | On top of the SMT and MC scheduling domains this adds the BOOK scheduling domain. This is useful for NUMA like machines which do not have an interface which tells which piece of memory is attached to which node or where the hardware performs striping. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100831082844.253053798@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* topology: alternate fix for ia64 tiger_defconfig build breakageLee Schermerhorn2010-08-09
| | | | | | | | | | | | | | | | Define stubs for the numa_*_id() generic percpu related functions for non-NUMA configurations in <asm-generic/topology.h> where the other non-numa stubs live. Fixes ia64 !NUMA build breakage -- e.g., tiger_defconfig Back out now unneeded '#ifndef CONFIG_NUMA' guards from ia64 smpboot.c Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Tested-by: Tony Luck <tony.luck@intel.com> Acked-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: Fix spelling of siblingMichael Neuling2010-06-29
| | | | | | | | | | | No logic changes, only spelling. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: linuxppc-dev@ozlabs.org Cc: David Howells <dhowells@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <15249.1277776921@neuling.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Add asymmetric group packing option for sibling domainMichael Neuling2010-06-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Check to see if the group is packed in a sched doman. This is primarily intended to used at the sibling level. Some cores like POWER7 prefer to use lower numbered SMT threads. In the case of POWER7, it can move to lower SMT modes only when higher threads are idle. When in lower SMT modes, the threads will perform better since they share less core resources. Hence when we have idle threads, we want them to be the higher ones. This adds a hook into f_b_g() called check_asym_packing() to check the packing. This packing function is run on idle threads. It checks to see if the busiest CPU in this domain (core in the P7 case) has a higher CPU number than what where the packing function is being run on. If it is, calculate the imbalance and return the higher busier thread as the busiest group to f_b_g(). Here we are assuming a lower CPU number will be equivalent to a lower SMT thread number. It also creates a new SD_ASYM_PACKING flag to enable this feature at any scheduler domain level. It also creates an arch hook to enable this feature at the sibling level. The default function doesn't enable this feature. Based heavily on patch from Peter Zijlstra. Fixes from Srivatsa Vaddagiri. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <20100608045702.2936CCC897@localhost.localdomain> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* numa: introduce numa_mem_id()- effective local memory node idLee Schermerhorn2010-05-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce numa_mem_id(), based on generic percpu variable infrastructure to track "nearest node with memory" for archs that support memoryless nodes. Define API in <linux/topology.h> when CONFIG_HAVE_MEMORYLESS_NODES defined, else stubs. Architectures will define HAVE_MEMORYLESS_NODES if/when they support them. Archs can override definitions of: numa_mem_id() - returns node number of "local memory" node set_numa_mem() - initialize [this cpus'] per cpu variable 'numa_mem' cpu_to_mem() - return numa_mem for specified cpu; may be used as lvalue Generic initialization of 'numa_mem' occurs in __build_all_zonelists(). This will initialize the boot cpu at boot time, and all cpus on change of numa_zonelist_order, or when node or memory hot-plug requires zonelist rebuild. Archs that support memoryless nodes will need to initialize 'numa_mem' for secondary cpus as they're brought on-line. [akpm@linux-foundation.org: fix build] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Cc: Tejun Heo <tj@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* numa: add generic percpu var numa_node_id() implementationLee Schermerhorn2010-05-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rework the generic version of the numa_node_id() function to use the new generic percpu variable infrastructure. Guard the new implementation with a new config option: CONFIG_USE_PERCPU_NUMA_NODE_ID. Archs which support this new implemention will default this option to 'y' when NUMA is configured. This config option could be removed if/when all archs switch over to the generic percpu implementation of numa_node_id(). Arch support involves: 1) converting any existing per cpu variable implementations to use this implementation. x86_64 is an instance of such an arch. 2) archs that don't use a per cpu variable for numa_node_id() will need to initialize the new per cpu variable "numa_node" as cpus are brought on-line. ia64 is an example. 3) Defining USE_PERCPU_NUMA_NODE_ID in arch dependent Kconfig--e.g., when NUMA is configured. This is required because I have retained the old implementation by default to allow archs to be modified incrementally, as desired. Subsequent patches will convert x86_64 and ia64 to use this implemenation. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Tejun Heo <tj@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Eric Whitney <eric.whitney@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: Fix vmark regression on big machinesMike Galbraith2010-01-21
| | | | | | | | | | | | | | SD_PREFER_SIBLING is set at the CPU domain level if power saving isn't enabled, leading to many cache misses on large machines as we traverse looking for an idle shared cache to wake to. Change the enabler of select_idle_sibling() to SD_SHARE_PKG_RESOURCES, and enable same at the sibling domain level. Reported-by: Lin Ming <ming.m.lin@intel.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1262612696.15495.15.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Disable SD_PREFER_LOCAL for MC/CPU domainsPeter Zijlstra2009-10-14
| | | | | | | | | | | | | | | Yanmin reported that both tbench and hackbench were significantly hurt by trying to keep tasks local on these domains, esp on small cache machines. So disable it in order to promote spreading outside of the cache domains. Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Mike Galbraith <efault@gmx.de> LKML-Reference: <1255083400.8802.15.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpumask: remove obsolete topology_core_siblings and ↵Rusty Russell2009-09-23
| | | | | | | | topology_thread_siblings: core There were replaced by topology_core_cpumask and topology_thread_cpumask. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* sched: Disable wakeup balancingPeter Zijlstra2009-09-16
| | | | | | | | | | | | | | | | | | | | | | | | Sysbench thinks SD_BALANCE_WAKE is too agressive and kbuild doesn't really mind too much, SD_BALANCE_NEWIDLE picks up most of the slack. On a dual socket, quad core, dual thread nehalem system: sysbench (--num_threads=16): SD_BALANCE_WAKE-: 13982 tx/s SD_BALANCE_WAKE+: 15688 tx/s kbuild (-j16): SD_BALANCE_WAKE-: 47.648295846 seconds time elapsed ( +- 0.312% ) SD_BALANCE_WAKE+: 47.608607360 seconds time elapsed ( +- 0.026% ) (same within noise) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Add SD_PREFER_LOCALPeter Zijlstra2009-09-16
| | | | | | | | | | | | And turn it on for NUMA and MC domains. This improves locality in balancing decisions by keeping up to capacity amount of tasks local before looking for idle CPUs. (and twice the capacity if SD_POWERSAVINGS_BALANCE is set.) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Reduce forkexec_idxPeter Zijlstra2009-09-15
| | | | | | | | | If we're looking to place a new task, we might as well find the idlest position _now_, not 1 tick ago. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Improve latencies and throughputMike Galbraith2009-09-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make the idle balancer more agressive, to improve a x264 encoding workload provided by Jason Garrett-Glaser: NEXT_BUDDY NO_LB_BIAS encoded 600 frames, 252.82 fps, 22096.60 kb/s encoded 600 frames, 250.69 fps, 22096.60 kb/s encoded 600 frames, 245.76 fps, 22096.60 kb/s NO_NEXT_BUDDY LB_BIAS encoded 600 frames, 344.44 fps, 22096.60 kb/s encoded 600 frames, 346.66 fps, 22096.60 kb/s encoded 600 frames, 352.59 fps, 22096.60 kb/s NO_NEXT_BUDDY NO_LB_BIAS encoded 600 frames, 425.75 fps, 22096.60 kb/s encoded 600 frames, 425.45 fps, 22096.60 kb/s encoded 600 frames, 422.49 fps, 22096.60 kb/s Peter pointed out that this is better done via newidle_idx, not via LB_BIAS, newidle balancing should look for where there is load _now_, not where there was load 2 ticks ago. Worst-case latencies are improved as well as no buddies means less vruntime spread. (as per prior lkml discussions) This change improves kbuild-peak parallelism as well. Reported-by: Jason Garrett-Glaser <darkshikari@gmail.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1253011667.9128.16.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix some domain tuningsPeter Zijlstra2009-09-15
| | | | | | | | CPU level should have WAKE_AFFINE, whereas ALLNODES is dubious. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Tweak wake_idxPeter Zijlstra2009-09-15
| | | | | | | | | | When merging select_task_rq_fair() and sched_balance_self() we lost the use of wake_idx, restore that and set them to 0 to make wake balancing more aggressive. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Merge select_task_rq_fair() and sched_balance_self()Peter Zijlstra2009-09-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The problem with wake_idle() is that is doesn't respect things like cpu_power, which means it doesn't deal well with SMT nor the recent RT interaction. To cure this, it needs to do what sched_balance_self() does, which leads to the possibility of merging select_task_rq_fair() and sched_balance_self(). Modify sched_balance_self() to: - update_shares() when walking up the domain tree, (it only called it for the top domain, but it should have done this anyway), which allows us to remove this ugly bit from try_to_wake_up(). - do wake_affine() on the smallest domain that contains both this (the waking) and the prev (the wakee) cpu for WAKE invocations. Then use the top-down balance steps it had to replace wake_idle(). This leads to the dissapearance of SD_WAKE_BALANCE and SD_WAKE_IDLE_FAR, with SD_WAKE_IDLE replaced with SD_BALANCE_WAKE. SD_WAKE_AFFINE needs SD_BALANCE_WAKE to be effective. Touch all topology bits to replace the old with new SD flags -- platforms might need re-tuning, enabling SD_BALANCE_WAKE conditionally on a NUMA distance seems like a good additional feature, magny-core and small nehalem systems would want this enabled, systems with slow interconnects would not. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: enable SD_WAKE_IDLEPeter Zijlstra2009-09-07
| | | | | | | | | Now that SD_WAKE_IDLE doesn't make pipe-test suck anymore, enable it by default for MC, CPU and NUMA domains. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Turn on SD_BALANCE_NEWIDLEIngo Molnar2009-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | Start the re-tuning of the balancer by turning on newidle. It improves hackbench performance and parallelism on a 4x4 box. The "perf stat --repeat 10" measurements give us: domain0 domain1 ....................................... -SD_BALANCE_NEWIDLE -SD_BALANCE_NEWIDLE: 2041.273208 task-clock-msecs # 9.354 CPUs ( +- 0.363% ) +SD_BALANCE_NEWIDLE -SD_BALANCE_NEWIDLE: 2086.326925 task-clock-msecs # 11.934 CPUs ( +- 0.301% ) +SD_BALANCE_NEWIDLE +SD_BALANCE_NEWIDLE: 2115.289791 task-clock-msecs # 12.158 CPUs ( +- 0.263% ) Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andreas Herrmann <andreas.herrmann3@amd.com> Cc: Andreas Herrmann <andreas.herrmann3@amd.com> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Clean up topology.hIngo Molnar2009-09-04
| | | | | | | | | | | | | | | | | Re-organize the flag settings so that it's visible at a glance which sched-domains flags are set and which not. With the new balancer code we'll need to re-tune these details anyway, so make it cleaner to make fewer mistakes down the road ;-) Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andreas Herrmann <andreas.herrmann3@amd.com> Cc: Andreas Herrmann <andreas.herrmann3@amd.com> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Add smt_gainPeter Zijlstra2009-09-04
| | | | | | | | | | | | | | The idea is that multi-threading a core yields more work capacity than a single thread, provide a way to express a static gain for threads. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Gautham R Shenoy <ego@in.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> LKML-Reference: <20090901083826.073345955@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* numa, cpumask: move numa_node_id default implementation to topology.hRusty Russell2009-03-13
| | | | | | | | | | | | | | | | | | | Impact: cleanup, potential bugfix Not sure what changed to expose this, but clearly that numa_node_id() doesn't belong in mmzone.h (the inline in gfp.h is probably overkill, too). In file included from include/linux/topology.h:34, from arch/x86/mm/numa.c:2: /home/rusty/patches-cpumask/linux-2.6/arch/x86/include/asm/topology.h:64:1: warning: "numa_node_id" redefined In file included from include/linux/topology.h:32, from arch/x86/mm/numa.c:2: include/linux/mmzone.h:770:1: warning: this is the location of the previous definition Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Mike Travis <travis@sgi.com> LKML-Reference: <200903132343.37661.rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpumask: replace node_to_cpumask with cpumask_of_node.Rusty Russell2009-03-13
| | | | | | | | | | Impact: cleanup node_to_cpumask (and the blecherous node_to_cpumask_ptr which contained a declaration) are replaced now everyone implements cpumask_of_node. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* cpumask: Use topology_core_cpumask()/topology_thread_cpumask()Rusty Russell2009-01-11
| | | | | | | | | | | | Impact: reduce stack usage, use new cpumask API. This actually uses topology_core_cpumask() and topology_thread_cpumask(), removing the only users of topology_core_siblings() and topology_thread_siblings() Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com> Cc: linux-net-drivers@solarflare.com
* sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0Vaidyanathan Srinivasan2008-12-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: change task balancing to save power more agressively Add SD_BALANCE_NEWIDLE flag at MC level and CPU level if sched_mc is set. This helps power savings and will not affect performance when sched_mc=0 Ingo and Mike Galbraith have optimised the SD flags by removing SD_BALANCE_NEWIDLE at MC and CPU level. This helps performance but hurts power savings since this slows down task consolidation by reducing the number of times load_balance is run. sched: fine-tune SD_MC_INIT commit 14800984706bf6936bbec5187f736e928be5c218 Author: Mike Galbraith <efault@gmx.de> Date: Fri Nov 7 15:26:50 2008 +0100 sched: re-tune balancing -- revert commit 9fcd18c9e63e325dbd2b4c726623f760788d5aa8 Author: Ingo Molnar <mingo@elte.hu> Date: Wed Nov 5 16:52:08 2008 +0100 This patch selectively enables SD_BALANCE_NEWIDLE flag only when sched_mc is set to 1 or 2. This helps power savings by task consolidation and also does not hurt performance at sched_mc=0 where all power saving optimisations are turned off. Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: convert BALANCE_FOR_xx_POWER to inline functionsVaidyanathan Srinivasan2008-12-19
| | | | | | | | | | | | | | | | | | Impact: cleanup BALANCE_FOR_MC_POWER and similar macros defined in sched.h are not constants and have various condition checks and significant amount of code that is not suitable to be contain in a macro. Also there could be side effects on the expressions passed to some of them like test_sd_parent(). This patch converts all complex macros related to power savings balance to inline functions. Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: let arch_update_cpu_topology indicate if topology changedHeiko Carstens2008-12-12
| | | | | | | | | Change arch_update_cpu_topology so it returns 1 if the cpu topology changed and 0 if it didn't change. This will be useful for the next patch which adds a call to this function in partition_sched_domains. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fine-tune SD_SIBLING_INITIngo Molnar2008-11-07
| | | | | | | | | | | | | | | | | | | | | | | fine-tune the HT sched-domains parameters as well. On a HT capable box, this increases lat_ctx performance from 23.87 usecs to 1.49 usecs: # before $ ./lat_ctx -s 0 2 "size=0k ovr=1.89 2 23.87 # after $ ./lat_ctx -s 0 2 "size=0k ovr=1.84 2 1.49 Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fine-tune SD_MC_INITMike Galbraith2008-11-07
| | | | | | | | | | | | | | | | Tune SD_MC_INIT the same way as SD_CPU_INIT: unset SD_BALANCE_NEWIDLE, and set SD_WAKE_BALANCE. This improves vmark by 5%: vmark 132102 125968 125497 messages/sec avg 127855.66 .984 vmark 139404 131719 131272 messages/sec avg 134131.66 1.033 Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> # *DOCUMENTATION*
* sched: re-tune balancingIngo Molnar2008-11-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: improve wakeup affinity on NUMA systems, tweak SMP systems Given the fixes+tweaks to the wakeup-buddy code, re-tweak the domain balancing defaults on NUMA and SMP systems. Turn on SD_WAKE_AFFINE which was off on x86 NUMA - there's no reason why we would not want to have wakeup affinity across nodes as well. (we already do this in the standard NUMA template.) lat_ctx on a NUMA box is particularly happy about this change: before: | phoenix:~/l> ./lat_ctx -s 0 2 | "size=0k ovr=2.60 | 2 5.70 after: | phoenix:~/l> ./lat_ctx -s 0 2 | "size=0k ovr=2.65 | 2 2.07 a 2.75x speedup. pipe-test is similarly happy about it too: | phoenix:~/sched-tests> ./pipe-test | 18.26 usecs/loop. | 14.70 usecs/loop. | 14.38 usecs/loop. | 10.55 usecs/loop. # +WAKE_AFFINE on domain0+domain1 | 8.63 usecs/loop. | 8.59 usecs/loop. | 9.03 usecs/loop. | 8.94 usecs/loop. | 8.96 usecs/loop. | 8.63 usecs/loop. Also: - disable SD_BALANCE_NEWIDLE on NUMA and SMP domains (keep it for siblings) - enable SD_WAKE_BALANCE on SMP domains Sysbench+postgresql improves all around the board, quite significantly: .28-rc3-11474e2c .28-rc3-11474e2c-tune ------------------------------------------------- 1: 571 688 +17.08% 2: 1236 1206 -2.55% 4: 2381 2642 +9.89% 8: 4958 5164 +3.99% 16: 9580 9574 -0.07% 32: 7128 8118 +12.20% 64: 7342 8266 +11.18% 128: 7342 8064 +8.95% 256: 7519 7884 +4.62% 512: 7350 7731 +4.93% ------------------------------------------------- SUM: 55412 59341 +6.62% So it's a win both for the runup portion, the peak area and the tail. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpu topology: always define CPU topology informationBen Hutchings2008-06-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This can result in an empty topology directory in sysfs, and requires in-kernel users to protect all uses with #ifdef - see <http://marc.info/?l=linux-netdev&m=120639033904472&w=2>. The documentation of CPU topology specifies what the defaults should be if only partial information is available from the hardware. So we can provide these defaults as a fallback. This patch: - Adds default definitions of the 4 topology macros to <linux/topology.h> - Changes drivers/base/topology.c to use the topology macros unconditionally and to cope with definitions that aren't lvalues - Updates documentation accordingly [ From: Andrew Morton <akpm@linux-foundation.org> - fold now-duplicated code - fix layout ] Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Cc: Vegard Nossum <vegard.nossum@gmail.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Mike Travis <travis@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: John Hawkes <hawkes@sgi.com> Cc: Zhang, Yanmin <yanmin.zhang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: re-tune NUMA topologiesIngo Molnar2008-05-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | improve the sysbench ramp-up phase and its peak throughput on a 16way NUMA box, by turning on WAKE_AFFINE: tip/sched tip/sched+wake-affine ------------------------------------------------- 1: 700 830 +15.65% 2: 1465 1391 -5.28% 4: 3017 3105 +2.81% 8: 5100 6021 +15.30% 16: 10725 10745 +0.19% 32: 10135 10150 +0.16% 64: 9338 9240 -1.06% 128: 8599 8252 -4.21% 256: 8475 8144 -4.07% ------------------------------------------------- SUM: 57558 57882 +0.56% this change also improves lat_ctx from 6.69 usecs to 1.11 usec: $ ./lat_ctx -s 0 2 "size=0k ovr=1.19 2 1.11 $ ./lat_ctx -s 0 2 "size=0k ovr=1.22 2 6.69 in sysbench it's an overall win with some weakness at the lots-of-clients side. That happens because we now under-balance this workload a bit. To counter that effect, turn on NEWIDLE: wake-idle wake-idle+newidle ------------------------------------------------- 1: 830 834 +0.43% 2: 1391 1401 +0.65% 4: 3105 3091 -0.43% 8: 6021 6046 +0.42% 16: 10745 10736 -0.08% 32: 10150 10206 +0.55% 64: 9240 9533 +3.08% 128: 8252 8355 +1.24% 256: 8144 8384 +2.87% ------------------------------------------------- SUM: 57882 58591 +1.21% as a bonus this not only improves the many-clients case but also improves the (more important) rampup phase. sysbench is a workload that quickly breaks down if the scheduler over-balances, so since it showed an improvement under NEWIDLE this change is definitely good.
* cpumask: reduce stack usage in SD_x_INIT initializersMike Travis2008-04-19
| | | | | | | | | | | | | | | | | | | * Remove empty cpumask_t (and all non-zero/non-null) variables in SD_*_INIT macros. Use memset(0) to clear. Also, don't inline the initializer functions to save on stack space in build_sched_domains(). * Merge change to include/linux/topology.h that uses the new node_to_cpumask_ptr function in the nr_cpus_node macro into this patch. Depends on: [mm-patch]: asm-generic-add-node_to_cpumask_ptr-macro.patch [sched-devel]: sched: add new set_cpus_allowed_ptr function Cc: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: add arch_update_cpu_topology hook.Heiko Carstens2008-03-21
| | | | | | | | | Will be called each time the scheduling domains are rebuild. Needed for architectures that don't have a static cpu topology. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: tune multi-core idle balancingIngo Molnar2008-03-18
| | | | | | | | WAKE_IDLE is too agressive on multi-core CPUs with the new wake-affine code, keep it on for SMT/HT balancing alone (where there's no cache affinity at all between logical CPUs). Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: whitespace cleanups in topology.hIngo Molnar2008-01-25
| | | | | | whitespace cleanups in topology.h. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: reactivate fork balancingIngo Molnar2008-01-25
| | | | | | reactivate fork balancing. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: enable wake-idle on CONFIG_SCHED_MC=yIngo Molnar2007-10-15
| | | | | | | most multicore CPUs today have shared L2 caches, so tune things so that the spreading amongst cores is more aggressive. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: reintroduce topology.h tuningsIngo Molnar2007-10-15
| | | | | | | reintroduce the 2.6.22 topology.h tunings again - they result in slightly better balancing. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [PATCH] sched: remove cache_hot_timeIngo Molnar2007-08-02
| | | | | | remove the last unused remains of cache_hot_time. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [PATCH] sched: small topology.h cleanupIngo Molnar2007-07-13
| | | | | | | | | trivial cleanup: LOCAL_DISTANCE and REMOTE_DISTANCE are only used in topology.h and inside an #ifndef section - limit their existence to that #ifndef. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: more agressive idle balancingIngo Molnar2007-07-09
| | | | | | | | | | the Linux scheduler is starving a number of workloads. So default to more agressive idle-balancing. This hurts lmbench context-switching numbers (which was the main reason we sucked at idle-balancing for such a long time) but the lmbench numbers are fine once the system is minimally utilized. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [PATCH] sched: remove SMT niceCon Kolivas2007-03-05
| | | | | | | | | | | | | | | | | | | | | | | | | | Remove the SMT-nice feature which idles sibling cpus on SMT cpus to facilitiate nice working properly where cpu power is shared. The idling of cpus in the presence of runnable tasks is considered too fragile, easy to break with outside code, and the complexity of managing this system if an architecture comes along with many logical cores sharing cpu power will be unworkable. Remove the associated per_cpu_gain variable in sched_domains used only by this code. Also: The reason is that with dynticks enabled, this code breaks without yet further tweaks so dynticks brought on the rapid demise of this code. So either we tweak this code or kill it off entirely. It was Ingo's preference to kill it off. Either way this needs to happen for 2.6.21 since dynticks has gone in. Signed-off-by: Con Kolivas <kernel@kolivas.org> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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