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* cfq-iosched: limit coop preemptionShaohua Li2009-11-03
| | | | | | | | | | | | | | | | | | | | | | CFQ has an optimization for cooperated applications. if several io-context have close requests, they will get boost. But the optimization get abused. Considering thread a, b, which work on one file. a reads sectors s, s+2, s+4, ...; b reads sectors s+1, s+3, s +5, ... Both a and b are sequential read, so they can open idle window. a reads a sector s and goes to idle window and wakeup b. b reads sector s+1, since in current implementation, cfq_should_preempt() thinks a and b are cooperators, b will preempt a. b then reads sector s+1 and goes to idle window and wakeup a. for the same reason, a will preempt b and reads s+2. a and b will continue the circle. The circle will be very long, and a and b will occupy whole disk queue. Other applications will nearly have no chance to run. Fix this limiting coop preempt until a queue is scheduled normally again. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix bad return value cfq_should_preempt()Jens Axboe2009-11-03
| | | | | | | | Commit a6151c3a5c8e1ff5a28450bc8d6a99a2a0add0a7 inadvertently reversed a preempt condition check, potentially causing a performance regression. Make the meta check correct again. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: avoid probable slice overrun when idlingCorrado Zoccolo2009-10-08
| | | | | | | | | | | If the average think time is larger than the remaining time slice for any given queue, don't allow it to idle. A succesful idle also means that we need to dispatch and complete a request, so if we don't even have time left for the idle process, we would overrun the slice in any case. Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: apply bool value where we return 0/1Jens Axboe2009-10-07
| | | | | | | | Saves 16 bytes of text, woohoo. But the more important point is that it makes the code more readable when returning bool for 0/1 cases. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix think time allowed for seekersCorrado Zoccolo2009-10-07
| | | | | | | | | CFQ enables idle only for processes that think less than the allowed idle time. Since idle time is lower for seeky queues, we should use the correct value in the comparison. Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix the slice residual signJens Axboe2009-10-06
| | | | | | | | | | We should subtract the slice residual from the rb tree key, since a negative residual count indicates that the cfqq overran its slice the last time. Hence we want to add the overrun time, to position it a bit further away in the service tree. Reported-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: abstract out the 'may this cfqq dispatch' logicJens Axboe2009-10-06
| | | | | | | Makes the whole thing easier to read, cfq_dispatch_requests() was a bit messy before. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: get rid of kblock_schedule_delayed_work()Jens Axboe2009-10-05
| | | | | | | | | | It was briefly introduced to allow CFQ to to delayed scheduling, but we ended up removing that feature again. So lets kill the function and export, and just switch CFQ back to the normal work schedule since it is now passing in a '0' delay from all call sites. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix possible problem with jiffies wraparoundCorrado Zoccolo2009-10-05
| | | | | | | | | | | The RR service tree is indexed by a key that is relative to current jiffies. This can cause problems on jiffies wraparound. The patch fixes it using time_before comparison, and changing the add_front path to use a relative number, too. Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix issue with rq-rq merging and fifo list orderingJens Axboe2009-10-05
| | | | | | | | | | cfq uses rq->start_time as the fifo indicator, but that field may get modified prior to cfq doing it's fifo list adjustment when a request gets merged with another request. This can cause the fifo list to become unordered. Reported-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: don't delay async queue if it hasn't dispatched at allJens Axboe2009-10-04
| | | | | | | | | We cannot delay for the first dispatch of the async queue if it hasn't dispatched at all, since that could present a local user DoS attack vector using an app that just did slow timed sync reads while filling memory. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: use assigned slice sync value, not defaultJens Axboe2009-10-03
| | | | | | | We should use the sysfs modified slice sync value, in case it differs from the default. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: rename 'desktop' sysfs entry to 'low_latency'Jens Axboe2009-10-03
| | | | | | | Don't think that's necessarily a perfect description of what this option fiddles with, but it's probably better than 'desktop'. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: implement slower async initiate and queue ramp upJens Axboe2009-10-03
| | | | | | | | This slowly ramps up the async queue depth based on the time passed since the sync IO, and doesn't allow async at all until a sync slice period has passed. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: delay async IO dispatch, if sync IO was just doneVivek Goyal2009-10-03
| | | | | | | | | | | o Do not allow more than max_dispatch requests from an async queue, if some sync request has finished recently. This is in the hope that sync activity is still going on in the system and we might receive a sync request soon. Most likely from a sync queue which finished a request and we did not enable idling on it. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: add a knob for desktop interactivenessJens Axboe2009-10-02
| | | | | | | | | | | | | | This is basically identical to what Vivek Goyal posted, but combined into one and labelled 'desktop' instead of 'fairness'. The goal is to continue to improve on the latency side of things as it relates to interactiveness, keeping the questionable bits under this sysfs tunable so it would be easy for throughput-only people to turn off. Apart from adding the interactive sysfs knob, it also adds the behavioural change of allowing slice idling even if the hardware does tagged command queuing. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2009-09-15
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (46 commits) powerpc64: convert to dynamic percpu allocator sparc64: use embedding percpu first chunk allocator percpu: kill lpage first chunk allocator x86,percpu: use embedding for 64bit NUMA and page for 32bit NUMA percpu: update embedding first chunk allocator to handle sparse units percpu: use group information to allocate vmap areas sparsely vmalloc: implement pcpu_get_vm_areas() vmalloc: separate out insert_vmalloc_vm() percpu: add chunk->base_addr percpu: add pcpu_unit_offsets[] percpu: introduce pcpu_alloc_info and pcpu_group_info percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward percpu: add @align to pcpu_fc_alloc_fn_t percpu: make @dyn_size mandatory for pcpu_setup_first_chunk() percpu: drop @static_size from first chunk allocators percpu: generalize first chunk allocator selection percpu: build first chunk allocators selectively percpu: rename 4k first chunk allocator to page percpu: improve boot messages percpu: fix pcpu_reclaim() locking ... Fix trivial conflict as by Tejun Heo in kernel/sched.c
| * Merge branch 'percpu-for-linus' into percpu-for-nextTejun Heo2009-08-14
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: arch/sparc/kernel/smp_64.c arch/x86/kernel/cpu/perf_counter.c arch/x86/kernel/setup_percpu.c drivers/cpufreq/cpufreq_ondemand.c mm/percpu.c Conflicts in core and arch percpu codes are mostly from commit ed78e1e078dd44249f88b1dd8c76dafb39567161 which substituted many num_possible_cpus() with nr_cpu_ids. As for-next branch has moved all the first chunk allocators into mm/percpu.c, the changes are moved from arch code to mm/percpu.c. Signed-off-by: Tejun Heo <tj@kernel.org>
| * \ Merge branch 'master' into for-nextTejun Heo2009-07-03
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull linus#master to merge PER_CPU_DEF_ATTRIBUTES and alpha build fix changes. As alpha in percpu tree uses 'weak' attribute instead of inline assembly, there's no need for __used attribute. Conflicts: arch/alpha/include/asm/percpu.h arch/mn10300/kernel/vmlinux.lds.S include/linux/percpu-defs.h
| * | | percpu: clean up percpu variable definitionsTejun Heo2009-06-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Percpu variable definition is about to be updated such that all percpu symbols including the static ones must be unique. Update percpu variable definitions accordingly. * as,cfq: rename ioc_count uniquely * cpufreq: rename cpu_dbs_info uniquely * xen: move nesting_count out of xen_evtchn_do_upcall() and rename it * mm: move ratelimits out of balance_dirty_pages_ratelimited_nr() and rename it * ipv4,6: rename cookie_scratch uniquely * x86 perf_counter: rename prev_left to pmc_prev_left, irq_entry to pmc_irq_entry and nmi_entry to pmc_nmi_entry * perf_counter: rename disable_count to perf_disable_count * ftrace: rename test_event_disable to ftrace_test_event_disable * kmemleak: rename test_pointer to kmemleak_test_pointer * mce: rename next_interval to mce_next_interval [ Impact: percpu usage cleanups, no duplicate static percpu var names ] Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Dave Jones <davej@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: linux-mm <linux-mm@kvack.org> Cc: David S. Miller <davem@davemloft.net> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andi Kleen <andi@firstfloor.org>
* | | | cfq: choose a new next_req when a request is dispatchedJeff Moyer2009-09-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch addresses http://bugzilla.kernel.org/show_bug.cgi?id=13401, a regression introduced in 2.6.30. From the bug report: Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | | | cfq: fix the log message after dispatched a requestShan Wei2009-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The blktrace tools can show process id when cfq dispatched a request, using cfq_log_cfqq() instead of cfq_log(). Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | | | cfq-iosched: get rid of must_alloc flagJens Axboe2009-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's not currently used, as pointed out by Gui Jianfeng <guijianfeng@cn.fujitsu.com>. We already check the wait_request flag to allow an idling queue priority allocation access, so we don't need this extra flag. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | | | bio: first step in sanitizing the bio->bi_rw flag testingJens Axboe2009-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Get rid of any functions that test for these bits and make callers use bio_rw_flagged() directly. Then it is at least directly apparent what variable and flag they check. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | | | cfq-iosched: no need to keep track of busy_rt_queuesVivek Goyal2009-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | o Get rid of busy_rt_queues infrastructure. Looks like it is redundant. o Once an RT queue gets request it will preempt any of the BE or IDLE queues immediately. Otherwise this queue will be put on service tree and scheduler will anyway select this queue before any of the BE or IDLE queue. Hence looks like there is no need to keep track of how many busy RT queues are currently on service tree. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | | | cfq-iosched: drain device queue before switching to a sync queueJens Axboe2009-09-11
| |_|/ |/| | | | | | | | | | | | | | | | | | | | To lessen the impact of async IO on sync IO, let the device drain of any async IO in progress when switching to a sync cfqq that has idling enabled. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | | cfq-iosched: reset oom_cfqq in cfq_set_request()Vivek Goyal2009-07-10
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | In case memory is scarce, we now default to oom_cfqq. Once memory is available again, we should allocate a new cfqq and stop using oom_cfqq for a particular io context. Once a new request comes in, check if we are using oom_cfqq, and if yes, try to allocate a new cfqq. Tested the patch by forcing the use of oom_cfqq and upon next request thread realized that it was using oom_cfqq and it allocated a new cfqq. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | cfq-iosched: remove redundant check for NULL cfqq in cfq_set_request()Shan Wei2009-07-01
| | | | | | | | | | | | | | | | With the changes for falling back to an oom_cfqq, we never fail to find/allocate a queue in cfq_get_queue(). So remove the check. Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | cfq-iosched: get rid of the need for __GFP_NOFAIL in cfq_find_alloc_queue()Jens Axboe2009-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Setup an emergency fallback cfqq that we allocate at IO scheduler init time. If the slab allocation fails in cfq_find_alloc_queue(), we'll just punt IO to that cfqq instead. This ensures that cfq_find_alloc_queue() never fails without having to ensure free memory. On cfqq lookup, always try to allocate a new cfqq if the given cfq io context has the oom_cfqq assigned. This ensures that we only temporarily punt to this shared queue. Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | cfq-iosched: move cfqq initialization out of cfq_find_alloc_queue()Jens Axboe2009-07-01
|/ | | | | | | | We're going to be needing that init code outside of that function to get rid of the __GFP_NOFAIL in cfqq allocation. Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq: remove extraneous '\n' in blktrace outputJeff Moyer2009-06-16
| | | | | | | I noticed a blank line in blktrace output. This patch fixes that. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq: cleanup for last_end_request in cfq_dataGui Jianfeng2009-06-16
| | | | | | | | Actually, last_end_request in cfq_data isn't used now. So lets just remove it. Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: prevent possible io_context->refcount overflowNikanth Karthikesan2009-06-10
| | | | | | | | | | | | | | | | | Currently io_context has an atomic_t(32-bit) as refcount. In the case of cfq, for each device against whcih a task does I/O, a reference to the io_context would be taken. And when there are multiple process sharing io_contexts(CLONE_IO) would also have a reference to the same io_context. Theoretically the possible maximum number of processes sharing the same io_context + the number of disks/cfq_data referring to the same io_context can overflow the 32-bit counter on a very high-end machine. Even though it is an improbable case, let us make it atomic_long_t. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: drop request->hard_* and *nr_sectorsTejun Heo2009-05-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | struct request has had a few different ways to represent some properties of a request. ->hard_* represent block layer's view of the request progress (completion cursor) and the ones without the prefix are supposed to represent the issue cursor and allowed to be updated as necessary by the low level drivers. The thing is that as block layer supports partial completion, the two cursors really aren't necessary and only cause confusion. In addition, manual management of request detail from low level drivers is cumbersome and error-prone at the very least. Another interesting duplicate fields are rq->[hard_]nr_sectors and rq->{hard_cur|current}_nr_sectors against rq->data_len and rq->bio->bi_size. This is more convoluted than the hard_ case. rq->[hard_]nr_sectors are initialized for requests with bio but blk_rq_bytes() uses it only for !pc requests. rq->data_len is initialized for all request but blk_rq_bytes() uses it only for pc requests. This causes good amount of confusion throughout block layer and its drivers and determining the request length has been a bit of black magic which may or may not work depending on circumstances and what the specific LLD is actually doing. rq->{hard_cur|current}_nr_sectors represent the number of sectors in the contiguous data area at the front. This is mainly used by drivers which transfers data by walking request segment-by-segment. This value always equals rq->bio->bi_size >> 9. However, data length for pc requests may not be multiple of 512 bytes and using this field becomes a bit confusing. In general, having multiple fields to represent the same property leads only to confusion and subtle bugs. With recent block low level driver cleanups, no driver is accessing or manipulating these duplicate fields directly. Drop all the duplicates. Now rq->sector means the current sector, rq->data_len the current total length and rq->bio->bi_size the current segment length. Everything else is defined in terms of these three and available only through accessors. * blk_recalc_rq_sectors() is collapsed into blk_update_request() and now handles pc and fs requests equally other than rq->sector update. This means that now pc requests can use partial completion too (no in-kernel user yet tho). * bio_cur_sectors() is replaced with bio_cur_bytes() as block layer now uses byte count as the primary data length. * blk_rq_pos() is now guranteed to be always correct. In-block users converted. * blk_rq_bytes() is now guaranteed to be always valid as is blk_rq_sectors(). In-block users converted. * blk_rq_sectors() is now guaranteed to equal blk_rq_bytes() >> 9. More convenient one is used. * blk_rq_bytes() and blk_rq_cur_bytes() are now inlined and take const pointer to request. [ Impact: API cleanup, single way to represent one property of a request ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: convert to pos and nr_sectors accessorsTejun Heo2009-05-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With recent cleanups, there is no place where low level driver directly manipulates request fields. This means that the 'hard' request fields always equal the !hard fields. Convert all rq->sectors, nr_sectors and current_nr_sectors references to accessors. While at it, drop superflous blk_rq_pos() < 0 test in swim.c. [ Impact: use pos and nr_sectors accessors ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Tested-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: Grant Likely <grant.likely@secretlab.ca> Tested-by: Adrian McMenamin <adrian@mcmen.demon.co.uk> Acked-by: Adrian McMenamin <adrian@mcmen.demon.co.uk> Acked-by: Mike Miller <mike.miller@hp.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Eric Moore <Eric.Moore@lsi.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Dario Ballabio <ballabio_dario@emc.com> Cc: David S. Miller <davem@davemloft.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: unsik Kim <donari75@gmail.com> Cc: Laurent Vivier <Laurent@lvivier.info> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: implement blk_rq_pos/[cur_]sectors() and convert obvious onesTejun Heo2009-05-11
| | | | | | | | | | | | | | | | | | | | | | | | | Implement accessors - blk_rq_pos(), blk_rq_sectors() and blk_rq_cur_sectors() which return rq->hard_sector, rq->hard_nr_sectors and rq->hard_cur_sectors respectively and convert direct references of the said fields to the accessors. This is in preparation of request data length handling cleanup. Geert : suggested adding const to struct request * parameter to accessors Sergei : spotted error in patch description [ Impact: cleanup ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Acked-by: Stephen Rothwell <sfr@canb.auug.org.au> Tested-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: Grant Likely <grant.likely@secretlab.ca> Ackec-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: kill blk_start_queueing()Tejun Heo2009-04-28
| | | | | | | | | | | blk_start_queueing() is identical to __blk_run_queue() except that it doesn't check for recursion. None of the current users depends on blk_start_queueing() running request_fn directly. Replace usages of blk_start_queueing() with [__]blk_run_queue() and kill it. [ Impact: removal of mostly duplicate interface function ] Signed-off-by: Tejun Heo <tj@kernel.org>
* cfq-iosched: cache prio_tree root in cfqq->p_rootJens Axboe2009-04-24
| | | | | | | | | | | | | | | Currently we look it up from ->ioprio, but ->ioprio can change if either the process gets its IO priority changed explicitly, or if cfq decides to temporarily boost it. So if we are unlucky, we can end up attempting to remove a node from a different rbtree root than where it was added. Fix this by using ->org_ioprio as the prio_tree index, since that will only change for explicit IO priority settings (not for a boost). Additionally cache the rbtree root inside the cfqq, then we don't have to add code to reinsert the cfqq in the prio_tree if IO priority changes. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix bug with aliased request and cooperation detectionJens Axboe2009-04-24
| | | | | | | | | | | | | cfq_prio_tree_lookup() should return the direct match, yet it always returns zero. Fix that. cfq_prio_tree_add() assumes that we don't get a direct match, while it is very possible that we do. Using O_DIRECT, you can have different cfqq with matching requests, since you don't have the page cache to serialize things for you. Fix this bug by only adding the cfqq if there isn't an existing match. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: clear ->prio_trees[] on cfqd allocJens Axboe2009-04-24
| | | | | | | Not strictly needed, but we should make it clear that we init the rbtree roots here. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: use the default seek distance when there aren't enough seek samplesJeff Moyer2009-04-22
| | | | | | | | | If the cfq io context doesn't have enough samples yet to provide a mean seek distance, then use the default threshold we have for seeky IO instead of defaulting to 0. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: make seek_mean converge more quicklyJeff Moyer2009-04-22
| | | | | | | | | | Right now, depending on the first sector to which a process issues I/O, the seek time may start out way out of whack. So make sure we start with 0 sectors in seek, instead of the offset of the first request issued. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: add close cooperator codeJens Axboe2009-04-15
| | | | | | | | | | | | | | | | | | | | | | If we have processes that are working in close proximity to each other on disk, we don't want to idle wait. Instead allow the close process to issue a request, getting better aggregate bandwidth. The anticipatory scheduler has similar checks, noop and deadline do not need it since they don't care about process <-> io mappings. The code for CFQ is a little more involved though, since we split request queues into per-process contexts. This fixes a performance problem with eg dump(8), since it uses several processes in some silly attempt to speed IO up. Even if dump(8) isn't really a valid case (it should be fixed by using CLONE_IO), there are other cases where we see close processes and where idling ends up hurting performance. Credit goes to Jeff Moyer <jmoyer@redhat.com> for writing the initial implementation. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: log responsible 'cfqq' in idle timer armJens Axboe2009-04-15
| | | | | | Makes it easier to read the traces. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: tweak kick logic a bit moreJens Axboe2009-04-15
| | | | | | | | | | We only kick the dispatch for an idling queue, if we think it's a (somewhat) fully merged request. Also allow a kick if we have other busy queues in the system, since we don't want to risk waiting for a potential merge in that case. It's better to get some work done and proceed. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: no need to save interrupts in cfq_kick_queue()Jens Axboe2009-04-15
| | | | | | | It's called from the workqueue handlers from process context, so we always have irqs enabled when entered. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: don't delay queue kick for a merged requestJens Axboe2009-04-15
| | | | | | | | | | | | | | | | | | | | | | | | "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> reports that commit b029195dda0129b427c6e579a3bb3ae752da3a93 introduced a regression of about 50% with sequential threaded read workloads. The test case is: tiotest -k0 -k1 -k3 -f 80 -t 32 which starts 32 threads each reading a 80MB file. Twiddle the kick queue logic so that we do start IO immediately, if it appears to be a fully merged request. We can't really detect that, so just check if the request is bigger than a page or not. The assumption is that since single bio issues will first queue a single request with just one page attached and then later do merges on that, if we already have more than a page worth of data in the request, then the request is most likely good to go. Verified that this doesn't cause a regression with the test case that commit b029195dda0129b427c6e579a3bb3ae752da3a93 was fixing. It does not, we still see maximum sized requests for the queue-then-merge cases. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: get rid of private SYNC/ASYNC definesJens Axboe2009-04-15
| | | | | | We can just use the block layer BLK_RW_SYNC/ASYNC defines now. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: use rw_is_sync() to see if rw flags are sync or notJens Axboe2009-04-15
| | | | Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: don't let idling interfere with pluggingJens Axboe2009-04-07
| | | | | | | | | | | | | When CFQ is waiting for a new request from a process, currently it'll immediately restart queuing when it sees such a request. This doesn't work very well with streamed IO, since we then end up splitting IO that would otherwise have been merged nicely. For a simple dd test, this causes 10x as many requests to be issued as we should have. Normally this goes unnoticed due to the low overhead of requests at the device side, but some hardware is very sensitive to request sizes and there it can cause big slow downs. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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