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* sched: fix mysql+oltp regressionMike Galbraith2008-08-11
| | | | | | | | | | | | | | | | | | | | | | | | | | Defer commit 6d299f1b53b84e2665f402d9bcc494800aba6386 to the next release. Testing of the tip/sched/clock tree revealed a mysql+oltp regression which bisection eventually traced back to this commit in mainline. Pertinent test results: Three run sysbench averages, throughput units in read/write requests/sec. clients 1 2 4 8 16 32 64 6e0534f 9646 17876 34774 33868 32230 30767 29441 2.6.26.1 9112 17936 34652 33383 31929 30665 29232 6d299f1 9112 14637 28370 33339 32038 30762 29204 Note: subsequent commits hide the majority of this regression until you apply the clock fixes, at which time it reemerges at full magnitude. We cannot see anything bad about the change itself so we defer it to the next release until this problem is fully analysed. Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fix warning in hrtick_start_fair()Peter Zijlstra2008-07-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | Benjamin Herrenschmidt reported: > I get that on ppc64 ... > > In file included from kernel/sched.c:1595: > kernel/sched_fair.c: In function ‘hrtick_start_fair’: > kernel/sched_fair.c:902: warning: comparison of distinct pointer types lacks a cast > > Probably harmless but annoying. s64 delta = slice - ran; --> delta = max(10000LL, delta); Probably ppc64's s64 is long vs long long.. I think hpa was looking at sanitizing all these 64bit types across the architectures. Use max_t with an explicit type meanwhile. Reported-by: Benjamin Herrenschmid <benh@kernel.crashing.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'sched/for-linus' of ↵Linus Torvalds2008-07-23
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: hrtick_enabled() should use cpu_active() sched, x86: clean up hrtick implementation sched: fix build error, provide partition_sched_domains() unconditionally sched: fix warning in inc_rt_tasks() to not declare variable 'rq' if it's not needed cpu hotplug: Make cpu_active_map synchronization dependency clear cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment (take 2) sched: rework of "prioritize non-migratable tasks over migratable ones" sched: reduce stack size in isolated_cpu_setup() Revert parts of "ftrace: do not trace scheduler functions" Fixed up conflicts in include/asm-x86/thread_info.h (due to the TIF_SINGLESTEP unification vs TIF_HRTICK_RESCHED removal) and kernel/sched_fair.c (due to cpu_active_map vs for_each_cpu_mask_nr() introduction).
| * Merge branch 'sched/urgent' into sched/develIngo Molnar2008-07-20
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| | * sched, x86: clean up hrtick implementationPeter Zijlstra2008-07-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | random uvesafb failures were reported against Gentoo: http://bugs.gentoo.org/show_bug.cgi?id=222799 and Mihai Moldovan bisected it back to: > 8f4d37ec073c17e2d4aa8851df5837d798606d6f is first bad commit > commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f > Author: Peter Zijlstra <a.p.zijlstra@chello.nl> > Date: Fri Jan 25 21:08:29 2008 +0100 > > sched: high-res preemption tick Linus suspected it to be hrtick + vm86 interaction and observed: > Btw, Peter, Ingo: I think that commit is doing bad things. They aren't > _incorrect_ per se, but they are definitely bad. > > Why? > > Using random _TIF_WORK_MASK flags is really impolite for doing > "scheduling" work. There's a reason that arch/x86/kernel/entry_32.S > special-cases the _TIF_NEED_RESCHED flag: we don't want to exit out of > vm86 mode unnecessarily. > > See the "work_notifysig_v86" label, and how it does that > "save_v86_state()" thing etc etc. Right, I never liked having to fiddle with those TIF flags. Initially I needed it because the hrtimer base lock could not nest in the rq lock. That however is fixed these days. Currently the only reason left to fiddle with the TIF flags is remote wakeups. We cannot program a remote cpu's hrtimer. I've been thinking about using the new and improved IPI function call stuff to implement hrtimer_start_on(). However that does require that smp_call_function_single(.wait=0) works from interrupt context - /me looks at the latest series from Jens - Yes that does seem to be supported, good. Here's a stab at cleaning this stuff up ... Mihai reported test success as well. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Mihai Moldovan <ionic@ionic.de> Cc: Michal Januszewski <spock@gentoo.org> Cc: Antonino Daplas <adaplas@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment ↵Max Krasnyansky2008-07-18
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (take 2) This is based on Linus' idea of creating cpu_active_map that prevents scheduler load balancer from migrating tasks to the cpu that is going down. It allows us to simplify domain management code and avoid unecessary domain rebuilds during cpu hotplug event handling. Please ignore the cpusets part for now. It needs some more work in order to avoid crazy lock nesting. Although I did simplfy and unify domain reinitialization logic. We now simply call partition_sched_domains() in all the cases. This means that we're using exact same code paths as in cpusets case and hence the test below cover cpusets too. Cpuset changes to make rebuild_sched_domains() callable from various contexts are in the separate patch (right next after this one). This not only boots but also easily handles while true; do make clean; make -j 8; done and while true; do on-off-cpu 1; done at the same time. (on-off-cpu 1 simple does echo 0/1 > /sys/.../cpu1/online thing). Suprisingly the box (dual-core Core2) is quite usable. In fact I'm typing this on right now in gnome-terminal and things are moving just fine. Also this is running with most of the debug features enabled (lockdep, mutex, etc) no BUG_ONs or lockdep complaints so far. I believe I addressed all of the Dmitry's comments for original Linus' version. I changed both fair and rt balancer to mask out non-active cpus. And replaced cpu_is_offline() with !cpu_active() in the main scheduler code where it made sense (to me). Signed-off-by: Max Krasnyanskiy <maxk@qualcomm.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Gregory Haskins <ghaskins@novell.com> Cc: dmitry.adamushko@gmail.com Cc: pj@sgi.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | Merge branch 'linus' into cpus4096Ingo Molnar2008-07-15
|\| | | | | | | | | | | | | | | | | | | Conflicts: arch/x86/xen/smp.c kernel/sched_rt.c net/iucv/iucv.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: add avg-overlap support to RT tasksGregory Haskins2008-07-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have the notion of tracking process-coupling (a.k.a. buddy-wake) via the p->se.last_wake / p->se.avg_overlap facilities, but it is only used for cfs to cfs interactions. There is no reason why an rt to cfs interaction cannot share in establishing a relationhip in a similar manner. Because PREEMPT_RT runs many kernel threads as FIFO priority, we often times have heavy interaction between RT threads waking CFS applications. This patch offers a substantial boost (50-60%+) in perfomance under those circumstances. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Cc: npiggin@suse.de Cc: rostedt@goodmis.org Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: make sched_{rt,fair}.c ifdefs more readableDhaval Giani2008-06-27
| | | | | | | | | | | | | | Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: bias effective_load() error towards failing wake_affine().Peter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | Measurement shows that the difference between cgroup:/ and cgroup:/foo wake_affine() results is that the latter succeeds significantly more. Therefore bias the calculations towards failing the test. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: incremental effective_load()Peter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | Increase the accuracy of the effective_load values. Not only consider the current increment (as per the attempted wakeup), but also consider the delta between when we last adjusted the shares and the current situation. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: correct wakeup weight calculationsPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rw_i = {2, 4, 1, 0} s_i = {2/7, 4/7, 1/7, 0} wakeup on cpu0, weight=1 rw'_i = {3, 4, 1, 0} s'_i = {3/8, 4/8, 1/8, 0} s_0 = S * rw_0 / \Sum rw_j -> \Sum rw_j = S*rw_0/s_0 = 1*2*7/2 = 7 (correct) s'_0 = S * (rw_0 + 1) / (\Sum rw_j + 1) = 1 * (2+1) / (7+1) = 3/8 (correct so we find that adding 1 to cpu0 gains 5/56 in weight if say the other cpu were, cpu1, we'd also have to calculate its 4/56 loss Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix mult overflowSrivatsa Vaddagiri2008-06-27
| | | | | | | | | | | | | | | | | | | | It was observed these mults can overflow. Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: optimize effective_load()Peter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | s_i = S * rw_i / \Sum_j rw_j -> \Sum_j rw_j = S * rw_i / s_i -> s'_i = S * (rw_i + w) / (\Sum_j rw_j + w) delta s = s' - s = S * (rw + w) / ((S * rw / s) + w) = s * (S * (rw + w) / (S * rw + s * w) - 1) a = S*(rw+w), b = S*rw + s*w delta s = s * (a-b) / b IOW, trade one divide for two multiplies Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix task_h_load()Peter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently task_h_load() computes the load of a task and uses that to either subtract it from the total, or add to it. However, removing or adding a task need not have any effect on the total load at all. Imagine adding a task to a group that is local to one cpu - in that case the total load of that cpu is unaffected. So properly compute addition/removal: s_i = S * rw_i / \Sum_j rw_j s'_i = S * (rw_i + wl) / (\Sum_j rw_j + wg) then s'_i - s_i gives the change in load. Where s_i is the shares for cpu i, S the group weight, rw_i the runqueue weight for that cpu, wl the weight we add (subtract) and wg the weight contribution to the runqueue. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix load scaling in group balancingPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | doing the load balance will change cfs_rq->load.weight (that's the whole point) but since that's part of the scale factor, we'll scale back with a different amount. Weight getting smaller would result in an inflated moved_load which causes it to stop balancing too soon. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: hierarchical load vs affine wakeupsPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | With hierarchical grouping we can't just compare task weight to rq weight - we need to scale the weight appropriately. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: simplify the group load balancerPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While thinking about the previous patch - I realized that using per domain aggregate load values in load_balance_fair() is wrong. We should use the load value for that CPU. By not needing per domain hierarchical load values we don't need to store per domain aggregate shares, which greatly simplifies all the math. It basically falls apart in two separate computations: - per domain update of the shares - per CPU update of the hierarchical load Also get rid of the move_group_shares() stuff - just re-compute the shares again after a successful load balance. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: no need to aggregate task_weightPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | We only need to know the task_weight of the busiest rq - nothing to do if there are no tasks there. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: kill task_group balancingSrivatsa Vaddagiri2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The idea was to balance groups until we've reached the global goal, however Vatsa rightly pointed out that we might never reach that goal this way - hence take out this logic. [ the initial rationale for this 'feature' was to promote max concurrency within a group - it does not however affect fairness ] Reported-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix sched_domain aggregationPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | Keeping the aggregate on the first cpu of the sched domain has two problems: - it could collide between different sched domains on different cpus - it could slow things down because of the remote accesses Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix wakeup granularity and buddy granularityPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Uncouple buddy selection from wakeup granularity. The initial idea was that buddies could run ahead as far as a normal task can - do this by measuring a pair 'slice' just as we do for a normal task. This means we can drop the wakeup_granularity back to 5ms. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: revert revert of: fair-group: SMP-nice for group schedulingPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | Try again.. Initial commit: 18d95a2832c1392a2d63227a7a6d433cb9f2037e Revert: 6363ca57c76b7b83639ca8c83fc285fa26a7880e Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix calc_delta_asym, #2Peter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ok, so why are we in this mess, it was: 1/w but now we mixed that rw in the mix like: rw/w rw being \Sum w suggests: fiddling w, we should also fiddle rw, humm? Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix calc_delta_asym()Peter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | calc_delta_asym() is supposed to do the same as calc_delta_fair() except linearly shrink the result for negative nice processes - this causes them to have a smaller preemption threshold so that they are more easily preempted. The problem is that for task groups se->load.weight is the per cpu share of the actual task group weight; take that into account. Also provide a debug switch to disable the asymmetry (which I still don't like - but it does greatly benefit some workloads) This would explain the interactivity issues reported against group scheduling. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: revert the revert of: weight calculationsPeter Zijlstra2008-06-27
| | | | | | | | | | | | | | | | | | | | | | | | Try again.. initial commit: 8f1bc385cfbab474db6c27b5af1e439614f3025c revert: f9305d4a0968201b2818dbed0dc8cb0d4ee7aeb3 Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * sched: fix SCHED_OTHER balance iterator to include all tasksGregory Haskins2008-06-06
| | | | | | | | | | | | | | | | | | | | | | The currently logic inadvertently skips the last task on the run-queue, resulting in missed balance opportunities. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: David Bahi <dbahi@novell.com> CC: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | Merge commit 'v2.6.26-rc9' into cpus4096Ingo Molnar2008-07-06
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| * sched: stop wake_affine from causing serious imbalanceMike Galbraith2008-05-29
| | | | | | | | | | | | | | | | | | Prevent short-running wakers of short-running threads from overloading a single cpu via wakeup affinity, and wire up disconnected debug option. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * revert ("sched: fair-group: SMP-nice for group scheduling")Ingo Molnar2008-05-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Yanmin Zhang reported: Comparing with 2.6.25, volanoMark has big regression with kernel 2.6.26-rc1. It's about 50% on my 8-core stoakley, 16-core tigerton, and Itanium Montecito. With bisect, I located the following patch: | 18d95a2832c1392a2d63227a7a6d433cb9f2037e is first bad commit | commit 18d95a2832c1392a2d63227a7a6d433cb9f2037e | Author: Peter Zijlstra <a.p.zijlstra@chello.nl> | Date: Sat Apr 19 19:45:00 2008 +0200 | | sched: fair-group: SMP-nice for group scheduling Revert it so that we get v2.6.25 behavior. Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * revert ("sched: fair: weight calculations")Ingo Molnar2008-05-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Yanmin Zhang reported: Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has many regressions with 2.6.26-rc1: 1) 8-core stoakley: 28%; 2) 16-core tigerton: 20%; 3) Itanium Montvale: 50%. Bisect located this patch: | 8f1bc385cfbab474db6c27b5af1e439614f3025c is first bad commit | commit 8f1bc385cfbab474db6c27b5af1e439614f3025c | Author: Peter Zijlstra <a.p.zijlstra@chello.nl> | Date: Sat Apr 19 19:45:00 2008 +0200 | | sched: fair: weight calculations Revert it to the 2.6.25 state. Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | core: use performance variant for_each_cpu_mask_nrMike Travis2008-05-23
|/ | | | | | | | | | | | Change references from for_each_cpu_mask to for_each_cpu_mask_nr where appropriate Reviewed-by: Paul Jackson <pj@sgi.com> Reviewed-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* sched: fix weight calculationsMike Galbraith2008-05-08
| | | | | | | | | | | | | | | | | | | | | | | | | The conversion between virtual and real time is as follows: dvt = rw/w * dt <=> dt = w/rw * dvt Since we want the fair sleeper granularity to be in real time, we actually need to do: dvt = - rw/w * l This bug could be related to the regression reported by Yanmin Zhang: | Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has lots | of regressions with 2.6.26-rc1: | | 1) 8-core stoakley: 28%; | 2) 16-core tigerton: 20%; | 3) Itanium Montvale: 50%. Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCKPeter Zijlstra2008-05-05
| | | | | | | | | | | | | | | | | | | | | | this replaces the rq->clock stuff (and possibly cpu_clock()). - architectures that have an 'imperfect' hardware clock can set CONFIG_HAVE_UNSTABLE_SCHED_CLOCK - the 'jiffie' window might be superfulous when we update tick_gtod before the __update_sched_clock() call in sched_clock_tick() - cpu_clock() might be implemented as: sched_clock_cpu(smp_processor_id()) if the accuracy proves good enough - how far can TSC drift in a single jiffie when considering the filtering and idle hooks? [ mingo@elte.hu: various fixes and cleanups ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fix debuggingMike Galbraith2008-05-05
| | | | | | | | | Revert debugging commit 7ba2e74ab5a0518bc953042952dd165724bc70c9. print_cfs_rq_tasks() can induce live-lock if a task is dequeued during list traversal. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fix SCHED_FAIR wake-idle logic errorGregory Haskins2008-05-05
| | | | | | | | | | | | | | | | | | | We currently use an optimization to skip the overhead of wake-idle processing if more than one task is assigned to a run-queue. The assumption is that the system must already be load-balanced or we wouldnt be overloaded to begin with. The problem is that we are looking at rq->nr_running, which may include RT tasks in addition to CFS tasks. Since the presence of RT tasks really has no bearing on the balance status of CFS tasks, this throws the calculation off. This patch changes the logic to only consider the number of CFS tasks when making the decision to optimze the wake-idle. Signed-off-by: Gregory Haskins <ghaskins@novell.com> CC: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: add statics, don't return void expressionsHarvey Harrison2008-05-05
| | | | | | | | | | | Noticed by sparse: kernel/sched.c:760:20: warning: symbol 'sched_feat_names' was not declared. Should it be static? kernel/sched.c:767:5: warning: symbol 'sched_feat_open' was not declared. Should it be static? kernel/sched_fair.c:845:3: warning: returning void-valued expression kernel/sched.c:4386:3: warning: returning void-valued expression Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fix normalized sleeperPeter Zijlstra2008-05-05
| | | | | | | | | Normalized sleeper uses calc_delta*() which requires that the rq load is already updated, so move account_entity_enqueue() before place_entity() Tested-by: Frans Pop <elendil@planet.nl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: debug: show a weight treePeter Zijlstra2008-04-19
| | | | | | | Print a tree of weights. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fair: weight calculationsPeter Zijlstra2008-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to level the hierarchy, we need to calculate load based on the root view. That is, each task's load is in the same unit. A / \ B 1 / \ 2 3 To compute 1's load we do: weight(1) -------------- rq_weight(A) To compute 2's load we do: weight(2) weight(B) ------------ * ----------- rq_weight(B) rw_weight(A) This yields load fractions in comparable units. The consequence is that it changes virtual time. We used to have: time_{i} vtime_{i} = ------------ weight_{i} vtime = \Sum vtime_{i} = time / rq_weight. But with the new way of load calculation we get that vtime equals time. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fair-group: de-couple load-balancing from the rb-treesPeter Zijlstra2008-04-19
| | | | | | | | De-couple load-balancing from the rb-trees, so that I can change their organization. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fair-group scheduling vs latencyPeter Zijlstra2008-04-19
| | | | | | | | Currently FAIR_GROUP sched grows the scheduler latency outside of sysctl_sched_latency, invert this so it stays within. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fair-group: SMP-nice for group schedulingPeter Zijlstra2008-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | Implement SMP nice support for the full group hierarchy. On each load-balance action, compile a sched_domain wide view of the full task_group tree. We compute the domain wide view when walking down the hierarchy, and readjust the weights when walking back up. After collecting and readjusting the domain wide view, we try to balance the tasks within the task_groups. The current approach is a naively balance each task group until we've moved the targeted amount of load. Inspired by Srivatsa Vaddsgiri's previous code and Abhishek Chandra's H-SMP paper. XXX: there will be some numerical issues due to the limited nature of SCHED_LOAD_SCALE wrt to representing a task_groups influence on the total weight. When the tree is deep enough, or the task weight small enough, we'll run out of bits. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Abhishek Chandra <chandra@cs.umn.edu> CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, cpuset: customize sched domains, coreHidetoshi Seto2008-04-19
| | | | | | | | | | | | | | | | | | [rebased for sched-devel/latest] - Add a new cpuset file, having levels: sched_relax_domain_level - Modify partition_sched_domains() and build_sched_domains() to take attributes parameter passed from cpuset. - Fill newidle_idx for node domains which currently unused but might be required if sched_relax_domain_level become higher. - We can change the default level by boot option 'relax_domain_level='. Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: prepatory code movementPeter Zijlstra2008-04-19
| | | | | Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: mix tasks and groupsDhaval Giani2008-04-19
| | | | | | | | | | | | This patch allows tasks and groups to exist in the same cfs_rq. With this change the CFS group scheduling follows a 1/(M+N) model from a 1/(1+N) fairness model where M tasks and N groups exist at the cfs_rq level. [a.p.zijlstra@chello.nl: rt bits and assorted fixes] Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: old sleeper bonusPeter Zijlstra2008-04-19
| | | | | Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fix regression with sched yieldPeter Zijlstra2008-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | Balbir Singh reported: > 1:mon> t > [c0000000e7677da0] c000000000067de0 .sys_sched_yield+0x6c/0xbc > [c0000000e7677e30] c000000000008748 syscall_exit+0x0/0x40 > --- Exception: c01 (System Call) at 00000400001d09e4 > SP (4000664cb10) is in userspace > 1:mon> r > cpu 0x1: Vector: 300 (Data Access) at [c0000000e7677aa0] > pc: c000000000068e50: .yield_task_fair+0x94/0xc4 > lr: c000000000067de0: .sys_sched_yield+0x6c/0xbc the check that should have avoided that is: /* * Are we the only task in the tree? */ if (unlikely(rq->load.weight == curr->se.load.weight)) return; But I guess that overlooks rt tasks, they also increase the load. So I guess something like this ought to fix it.. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: remove sysctl_sched_batch_wakeup_granularityIngo Molnar2008-04-19
| | | | | | it's unused. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: fix wakeup granularity for buddiesPeter Zijlstra2008-04-19
| | | | | | | | | | The wakeup buddy logic didn't use the same wakeup granularity logic as the wakeup preemption did, this might cause the ->next buddy to be selected past the point where we would have preempted had the task been a single running instance. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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