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2019-11-21block: add iostat counters for flush requestsKonstantin Khlebnikov1-2/+12
Requests that triggers flushing volatile writeback cache to disk (barriers) have significant effect to overall performance. Block layer has sophisticated engine for combining several flush requests into one. But there is no statistics for actual flushes executed by disk. Requests which trigger flushes usually are barriers - zero-size writes. This patch adds two iostat counters into /sys/class/block/$dev/stat and /proc/diskstats - count of completed flush requests and their total time. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-11docs: block: null_blk: enhance document styleAndré Almeida1-15/+18
Use proper ReST syntax for chapters. Add more information to enhance standardization in the file and to make the rendering more homogeneous. Add a SPDX identifier. Mark single-queue mode as deprecated. Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-03Documenation: switching-sched: Remove notes about elevator argumentMarcos Paulo de Souza1-4/+0
This argument was ignored since blk-mq was set as default, so remove it from documentation. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com> .txt file is now .rst Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-16Merge tag 'docs/v5.3-1' of ↵Linus Torvalds18-335/+536
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media Pull rst conversion of docs from Mauro Carvalho Chehab: "As agreed with Jon, I'm sending this big series directly to you, c/c him, as this series required a special care, in order to avoid conflicts with other trees" * tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits) docs: kbuild: fix build with pdf and fix some minor issues docs: block: fix pdf output docs: arm: fix a breakage with pdf output docs: don't use nested tables docs: gpio: add sysfs interface to the admin-guide docs: locking: add it to the main index docs: add some directories to the main documentation index docs: add SPDX tags to new index files docs: add a memory-devices subdir to driver-api docs: phy: place documentation under driver-api docs: serial: move it to the driver-api docs: driver-api: add remaining converted dirs to it docs: driver-api: add xilinx driver API documentation docs: driver-api: add a series of orphaned documents docs: admin-guide: add a series of orphaned documents docs: cgroup-v1: add it to the admin-guide book docs: aoe: add it to the driver-api book docs: add some documentation dirs to the driver-api book docs: driver-model: move it to the driver-api book docs: lp855x-driver.rst: add it to the driver-api book ...
2019-07-15docs: block: fix pdf outputMauro Carvalho Chehab1-4/+5
Add an extra blank line and use a markup for the enumberated list, in order to make it possible to build the block book on pdf format. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-15docs: cgroup-v1: add it to the admin-guide bookMauro Carvalho Chehab1-1/+1
Those files belong to the admin guide, so add them. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-15docs: add some documentation dirs to the driver-api bookMauro Carvalho Chehab1-1/+1
Those are subsystem docs, with a mix of kABI and user-faced docs. While they're not split, keep the dirs where they are, adding just a pointer to the main index. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-15docs: block: convert to ReSTMauro Carvalho Chehab18-332/+532
Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-10block: Remove unused definitionsDamien Le Moal1-5/+0
The ELV_MQUEUE_XXX definitions in include/linux/elevator.h are unused since the removal of elevator_may_queue_fn in kernel 5.0. Remove these definitions and also remove the documentation of elevator_may_queue_fn in Documentiation/block/biodoc.txt. Acked-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-09Merge tag 'for-5.3/block-20190708' of git://git.kernel.dk/linux-blockLinus Torvalds3-28/+49
Pull block updates from Jens Axboe: "This is the main block updates for 5.3. Nothing earth shattering or major in here, just fixes, additions, and improvements all over the map. This contains: - Series of documentation fixes (Bart) - Optimization of the blk-mq ctx get/put (Bart) - null_blk removal race condition fix (Bob) - req/bio_op() cleanups (Chaitanya) - Series cleaning up the segment accounting, and request/bio mapping (Christoph) - Series cleaning up the page getting/putting for bios (Christoph) - block cgroup cleanups and moving it to where it is used (Christoph) - block cgroup fixes (Tejun) - Series of fixes and improvements to bcache, most notably a write deadlock fix (Coly) - blk-iolatency STS_AGAIN and accounting fixes (Dennis) - Series of improvements and fixes to BFQ (Douglas, Paolo) - debugfs_create() return value check removal for drbd (Greg) - Use struct_size(), where appropriate (Gustavo) - Two lighnvm fixes (Heiner, Geert) - MD fixes, including a read balance and corruption fix (Guoqing, Marcos, Xiao, Yufen) - block opal shadow mbr additions (Jonas, Revanth) - sbitmap compare-and-exhange improvemnts (Pavel) - Fix for potential bio->bi_size overflow (Ming) - NVMe pull requests: - improved PCIe suspent support (Keith Busch) - error injection support for the admin queue (Akinobu Mita) - Fibre Channel discovery improvements (James Smart) - tracing improvements including nvmetc tracing support (Minwoo Im) - misc fixes and cleanups (Anton Eidelman, Minwoo Im, Chaitanya Kulkarni)" - Various little fixes and improvements to drivers and core" * tag 'for-5.3/block-20190708' of git://git.kernel.dk/linux-block: (153 commits) blk-iolatency: fix STS_AGAIN handling block: nr_phys_segments needs to be zero for REQ_OP_WRITE_ZEROES blk-mq: simplify blk_mq_make_request() blk-mq: remove blk_mq_put_ctx() sbitmap: Replace cmpxchg with xchg block: fix .bi_size overflow block: sed-opal: check size of shadow mbr block: sed-opal: ioctl for writing to shadow mbr block: sed-opal: add ioctl for done-mark of shadow mbr block: never take page references for ITER_BVEC direct-io: use bio_release_pages in dio_bio_complete block_dev: use bio_release_pages in bio_unmap_user block_dev: use bio_release_pages in blkdev_bio_end_io iomap: use bio_release_pages in iomap_dio_bio_end_io block: use bio_release_pages in bio_map_user_iov block: use bio_release_pages in bio_unmap_user block: optionally mark pages dirty in bio_release_pages block: move the BIO_NO_PAGE_REF check into bio_release_pages block: skd_main.c: Remove call to memset after dma_alloc_coherent block: mtip32xx: Remove call to memset after dma_alloc_coherent ...
2019-07-08Merge branch 'for-5.3' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: "Documentation updates and the addition of cgroup_parse_float() which will be used by new controllers including blk-iocost" * 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: docs: cgroup-v1: convert docs to ReST and rename to *.rst cgroup: Move cgroup_parse_float() implementation out of CONFIG_SYSFS cgroup: add cgroup_parse_float()
2019-06-29block, documentation: Document discard_zeroes_data, fua, ↵Bart Van Assche1-0/+20
max_discard_segments and write_zeroes_max_bytes Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-29block, documentation: Explain the word 'segments'Bart Van Assche1-4/+6
Several block layer users who are not kernel developers do not know that the word 'segment' refers to an element in a DMA scatter/gather list. Make the block layer documentation easier to understand by stating explicitly what the word 'segment' stands for. Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-29block, documentation: Sort queue sysfs attribute names alphabeticallyBart Van Assche1-15/+15
Commit f9824952ee1c ("block: update sysfs documentation") # v5.0 broke the alphabetical order of the sysfs attribute names. List queue sysfs attribute names alphabetically. Cc: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-29block, documentation: Fix wbt_lat_usec documentationBart Van Assche1-2/+2
Fix the spelling of the wbt_lat_usec sysfs attribute. Fixes: 87760e5eef35 ("block: hook up writeback throttling") # v4.10. Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20block: rename CONFIG_DEBUG_BLK_CGROUP to CONFIG_BFQ_CGROUP_DEBUGChristoph Hellwig1-6/+6
This option is entirely bfq specific, give it an appropinquate name. Also make it depend on CONFIG_BFQ_GROUP_IOSCHED in Kconfig, as all the functionality already does so anyway. Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20block: remove the bi_phys_segments field in struct bioChristoph Hellwig1-1/+0
We only need the number of segments in the blk-mq submission path. Remove the field from struct bio, and return it from a variant of blk_queue_split instead of that it can passed as an argument to those functions that need the value. This also means we stop recounting segments except for cloning and partial segments. To keep the number of arguments in this how path down remove pointless struct request_queue arguments from any of the functions that had it and grew a nr_segs argument. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-14docs: cgroup-v1: convert docs to ReST and rename to *.rstMauro Carvalho Chehab1-1/+1
Convert the cgroup-v1 files to ReST format, in order to allow a later addition to the admin-guide. The conversion is actually: - add blank lines and identation in order to identify paragraphs; - fix tables markups; - add some lists markups; - mark literal blocks; - adjust title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-06-13block/switching-sched.txt: Update to blk-mq schedulersAndreas Herrmann1-10/+8
Remove references to CFQ and legacy block layer which are gone. Update example with what's available under blk-mq. Signed-off-by: Andreas Herrmann <aherrmann@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-09block: null: Add documentation for "zone_nr_conv" paramMinwoo Im1-0/+4
zone_nr_conv module parameter was introduced by a commit ea2c18e1("null_blk: Add conventional zone configuration for zoned support"). This patch describes "zone_nr_conv" module parameter to the document. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-01doc, block, bfq: add information on bfq execution timePaolo Valente1-7/+22
The execution time of BFQ has been slightly lowered. Report the new execution time in BFQ documentation. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-15block: document usage of bio iterator helpersMing Lei1-0/+25
Now multi-page bvec is supported, some helpers may return page by page, meantime some may return segment by segment, this patch documents the usage. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-01-09block: doc: add slice_idle_us to bfq documentationJohn Pittman1-0/+7
Of the tunables available for the bfq I/O scheduler, the only one missing from the documentation in 'Documentation/block/bfq-iosched.txt' is slice_idle_us. Add this tunable to the documentation and a short explanation of its purpose. Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: John Pittman <jpittman@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-01-06null_blk: add zoned config support informationJohn Pittman1-1/+2
If the kernel is built without CONFIG_BLK_DEV_ZONED, a modprobe of the null_blk driver with zoned=1 fails with 'Invalid argument'. This can be confusing to users, prompting a search as to why the parameter is invalid. To assist in that search, add a bit more information to the failure, additionally adding to the documentation that CONFIG_BLK_DEV_ZONED is needed for zoned=1. Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: John Pittman <jpittman@redhat.com> Added null_blk prefix to error message. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-01-04block: add documentation for io_timeoutWeiping Zhang1-0/+7
Add documentation for /sys/block/<disk>/queue/io_timeout. Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-16block: update sysfs documentationDamien Le Moal1-1/+28
Add the description of the zoned, nr_zones and chunk_sectors sysfs queue attributes to Documentation/block/queue-sysfs.txt. The description of the zoned and chunk_sector attributes are mostly copied from ABI/testing/sysfs-block (added a typo fix). While at it, also fix a typo in the description of the io_poll_delay attribute. nr_zones description is also added to ABI/testing/sysfs-block and contact email address updated for the zoned attribute. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove legacy IO schedulersJens Axboe1-291/+0
Retain the deadline documentation, as that carries over to mq-deadline as well. Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove legacy rq taggingJens Axboe1-88/+0
It's now unused, kill it. Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-09Drop all 00-INDEX files from Documentation/Henrik Austad1-34/+0
This is a respin with a wider audience (all that get_maintainer returned) and I know this spams a *lot* of people. Not sure what would be the correct way, so my apologies for ruining your inbox. The 00-INDEX files are supposed to give a summary of all files present in a directory, but these files are horribly out of date and their usefulness is brought into question. Often a simple "ls" would reveal the same information as the filenames are generally quite descriptive as a short introduction to what the file covers (it should not surprise anyone what Documentation/sched/sched-design-CFS.txt covers) A few years back it was mentioned that these files were no longer really needed, and they have since then grown further out of date, so perhaps it is time to just throw them out. A short status yields the following _outdated_ 00-INDEX files, first counter is files listed in 00-INDEX but missing in the directory, last is files present but not listed in 00-INDEX. List of outdated 00-INDEX: Documentation: (4/10) Documentation/sysctl: (0/1) Documentation/timers: (1/0) Documentation/blockdev: (3/1) Documentation/w1/slaves: (0/1) Documentation/locking: (0/1) Documentation/devicetree: (0/5) Documentation/power: (1/1) Documentation/powerpc: (0/5) Documentation/arm: (1/0) Documentation/x86: (0/9) Documentation/x86/x86_64: (1/1) Documentation/scsi: (4/4) Documentation/filesystems: (2/9) Documentation/filesystems/nfs: (0/2) Documentation/cgroup-v1: (0/2) Documentation/kbuild: (0/4) Documentation/spi: (1/0) Documentation/virtual/kvm: (1/0) Documentation/scheduler: (0/2) Documentation/fb: (0/1) Documentation/block: (0/1) Documentation/networking: (6/37) Documentation/vm: (1/3) Then there are 364 subdirectories in Documentation/ with several files that are missing 00-INDEX alltogether (and another 120 with a single file and no 00-INDEX). I don't really have an opinion to whether or not we /should/ have 00-INDEX, but the above 00-INDEX should either be removed or be kept up to date. If we should keep the files, I can try to keep them updated, but I rather not if we just want to delete them anyway. As a starting point, remove all index-files and references to 00-INDEX and see where the discussion is going. Signed-off-by: Henrik Austad <henrik@austad.us> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Just-do-it-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Jens Axboe <axboe@kernel.dk> Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Mark Brown <broonie@kernel.org> Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: [Almost everybody else] Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-07-18block: Track DISCARD statistics and output them in stat and diskstatMichael Callahan1-12/+16
Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09null_blk: add zone supportMatias Bjørling1-0/+7
Adds support for exposing a null_blk device through the zone device interface. The interface is managed with the parameters zoned and zone_size. If zoned is set, the null_blk instance registers as a zoned block device. The zone_size parameter defines how big each zone will be. Signed-off-by: Matias Bjørling <matias.bjorling@wdc.com> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-15block: remov blk_queue_invalidate_tagsChristoph Hellwig1-14/+1
This function is entirely unused, so remove it and the tag_queue_busy member of struct request_queue. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-04Merge tag 'docs-4.18' of git://git.lwn.net/linuxLinus Torvalds1-7/+14
Pull documentation updates from Jonathan Corbet: "There's been a fair amount of work in the docs tree this time around, including: - Extensive RST conversions and organizational work in the memory-management docs thanks to Mike Rapoport. - An update of Documentation/features from Andrea Parri and a script to keep it updated. - Various LICENSES updates from Thomas, along with a script to check SPDX tags. - Work to fix dangling references to documentation files; this involved a fair number of one-liner comment changes outside of Documentation/ ... and the usual list of documentation improvements, typo fixes, etc" * tag 'docs-4.18' of git://git.lwn.net/linux: (103 commits) Documentation: document hung_task_panic kernel parameter docs/admin-guide/mm: add high level concepts overview docs/vm: move ksm and transhuge from "user" to "internals" section. docs: Use the kerneldoc comments for memalloc_no*() doc: document scope NOFS, NOIO APIs docs: update kernel versions and dates in tables docs/vm: transhuge: split userspace bits to admin-guide/mm/transhuge docs/vm: transhuge: minor updates docs/vm: transhuge: change sections order Documentation: arm: clean up Marvell Berlin family info Documentation: gpio: driver: Fix a typo and some odd grammar docs: ranoops.rst: fix location of ramoops.txt scripts/documentation-file-ref-check: rewrite it in perl with auto-fix mode docs: uio-howto.rst: use a code block to solve a warning mm, THP, doc: Add document for thp_swpout/thp_swpout_fallback w1: w1_io.c: fix a kernel-doc warning Documentation/process/posting: wrap text at 80 cols docs: admin-guide: add cgroup-v2 documentation Revert "Documentation/features/vm: Remove arch support status file for 'pte_special'" Documentation: refcount-vs-atomic: Update reference to LKMM doc. ...
2018-05-25null_blk: add blocking description and remove lightnvmLiu Bo1-3/+6
- The description of 'blocking' is missing in null_blk.txt - The 'lightnvm' parameter has been removed in null_blk.c This updates both in null_blk.txt. Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-08Documentation: block: cmdline-partition.txt fixes and additionsRandy Dunlap1-7/+14
Make the description of the kernel command line option "blkdevparts" a bit more flowing and readable. Fix a few typos. Add the optional <size> and <offset> suffixes. Note that size can be "-" to indicate all of the remaining space. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Cai Zhiyong <caizhiyong@huawei.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-11-14block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUPLuca Miccio1-6/+32
BFQ currently creates, and updates, its own instance of the whole set of blkio statistics that cfq creates. Yet, from the comments of Tejun Heo in [1], it turned out that most of these statistics are meant/useful only for debugging. This commit makes BFQ create the latter, debugging statistics only if the option CONFIG_DEBUG_BLK_CGROUP is set. By doing so, this commit also enables BFQ to enjoy a high perfomance boost. The reason is that, if CONFIG_DEBUG_BLK_CGROUP is not set, then BFQ has to update far fewer statistics, and, in particular, not the heaviest to update. To give an idea of the benefits, if CONFIG_DEBUG_BLK_CGROUP is not set, then, on an Intel i7-4850HQ, and with 8 threads doing random I/O in parallel on null_blk (configured with 0 latency), the throughput of BFQ grows from 310 to 400 KIOPS (+30%). We have measured similar or even much higher boosts with other CPUs: e.g., +45% with an ARM CortexTM-A53 Octa-core. Our results have been obtained and can be reproduced very easily with the script in [1]. [1] https://www.spinics.net/lists/linux-block/msg18943.html Suggested-by: Tejun Heo <tj@kernel.org> Suggested-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Lee Tibbert <lee.tibbert@gmail.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Luca Miccio <lucmiccio@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-14block, bfq: update blkio stats outside the scheduler lockPaolo Valente1-3/+3
bfq invokes various blkg_*stats_* functions to update the statistics contained in the special files blkio.bfq.* in the blkio controller groups, i.e., the I/O accounting related to the proportional-share policy provided by bfq. The execution of these functions takes a considerable percentage, about 40%, of the total per-request execution time of bfq (i.e., of the sum of the execution time of all the bfq functions that have to be executed to process an I/O request from its creation to its destruction). This reduces the request-processing rate sustainable by bfq noticeably, even on a multicore CPU. In fact, the bfq functions that invoke blkg_*stats_* functions cannot be executed in parallel with the rest of the code of bfq, because both are executed under the same same per-device scheduler lock. To reduce this slowdown, this commit moves, wherever possible, the invocation of these functions (more precisely, of the bfq functions that invoke blkg_*stats_* functions) outside the critical sections protected by the scheduler lock. With this change, and with all blkio.bfq.* statistics enabled, the throughput grows, e.g., from 250 to 310 KIOPS (+25%) on an Intel i7-4850HQ, in case of 8 threads doing random I/O in parallel on null_blk, with the latter configured with 0 latency. We obtained the same or higher throughput boosts, up to +30%, with other processors (some figures are reported in the documentation). For our tests, we used the script [1], with which our results can be easily reproduced. NOTE. This commit still protects the invocation of blkg_*stats_* functions with the request_queue lock, because the group these functions are invoked on may otherwise disappear before or while these functions are executed. Fortunately, tests without even this lock show, by difference, that the serialization caused by this lock has a little impact (at most ~5% of throughput reduction). [1] https://github.com/Algodev-github/IOSpeed Tested-by: Lee Tibbert <lee.tibbert@gmail.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Luca Miccio <lucmiccio@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-14doc, block, bfq: update max IOPS sustainable with BFQPaolo Valente1-6/+11
We have investigated more deeply the performance of BFQ, in terms of number of IOPS that can be processed by the CPU when BFQ is used as I/O scheduler. In more detail, using the script [1], we have measured the number of IOPS reached on top of a null block device configured with zero latency, as a function of the workload (sequential read, sequential write, random read, random write) and of the system (we considered desktops, laptops and embedded systems). Basing on the resulting figures, with this commit we update the current, conservative IOPS range reported in BFQ documentation. In particular, the documentation now reports, for each of three different systems, the lowest number of IOPS obtained for that system with the above test (namely, the value obtained with the workload leading to the lowest IOPS). [1] https://github.com/Algodev-github/IOSpeed Reviewed-by: Lee Tibbert <lee.tibbert@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Luca Miccio <lucmiccio@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10block: remove __bio_kmap_atomicChristoph Hellwig1-6/+5
This helper doesn't buy us much over calling kmap_atomic directly. In fact in the only caller it does a bit of useless work as the caller already has the bvec at hand, and said caller would even buggy for a multi-segment bio due to the use of this helper. So just remove it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-10block: kill bio_kmap/kunmap_irq()Jens Axboe1-2/+2
There are no users of it anymore. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-07null_blk: add an usage for shared tags in documentationMinwoo Im1-0/+5
Add usage explanation for a shared_tags, introduced by commit: 82f402fefa50 ("null_blk: add support for shared tags") Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Reworded slightly. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-07null_blk: fix default values in documentationMinwoo Im1-2/+2
null_blk.c has initial value of (1) nr_devices as 1. (2) completion_nsec as 10,000ns, not 10.000ns. documentation should be updated for fixes above. Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13null_blk: add usage hints for no_schedweiping zhang1-0/+4
This parameter provide an option to disable io scheduler when nullb* in multi-queue mode. Signed-off-by: weiping zhang <zhangweiping@didichuxing.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13null_blk: update usage hints for submit_queuesweiping zhang1-3/+3
update the range of submits_queues, and correct usage hints. Signed-off-by: weiping zhang <zhangweiping@didichuxing.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-31doc, block, bfq: better describe how to properly configure bfqPaolo Valente1-24/+54
Many users have reported the lack of an HOWTO for properly configuring bfq as a function of the goal one wants to achieve (max responsiveness, max throughput, ...). In fact, all needed details are already provided in the documentation file bfq-iosched.txt. Yet the document lacks guidance on which parameter descriptions to look at. This commit adds some simple direction. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Reviewed-by: Jeremy Hickman <jeremywh7@gmail.com> Reviewed-by: Laurentiu Nicola <lnicola@dend.ro> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-31doc, block, bfq: fix some typos and remove stale stuffPaolo Valente1-56/+10
In addition to containing some typos and stale sentences, the file bfq-iosched.txt still mentioned a set of sysfs parameters that have been removed from this version of bfq. This commit fixes all these issues. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Reviewed-by: Jeremy Hickman <jeremywh7@gmail.com> Reviewed-by: Laurentiu Nicola <lnicola@dend.ro> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-03bio-integrity: fold bio_integrity_enabled to bio_integrity_prepDmitry Monakhov1-4/+2
Currently all integrity prep hooks are open-coded, and if prepare fails we ignore it's code and fail bio with EIO. Let's return real error to upper layer, so later caller may react accordingly. In fact no one want to use bio_integrity_prep() w/o bio_integrity_enabled, so it is reasonable to fold it in to one function. Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> [hch: merged with the latest block tree, return bool from bio_integrity_prep] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-18block: remove bio_clone() and all references.NeilBrown1-1/+1
bio_clone() is no longer used. Only bio_clone_bioset() or bio_clone_fast(). This is for the best, as bio_clone() used fs_bio_set, and filesystems are unlikely to want to use bio_clone(). So remove bio_clone() and all references. This includes a fix to some incorrect documentation. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-05-10block, bfq: stress that low_latency must be off to get max throughputPaolo Valente1-1/+16
The introduction of the BFQ and Kyber I/O schedulers has triggered a new wave of I/O benchmarks. Unfortunately, comments and discussions on these benchmarks confirm that there is still little awareness that it is very hard to achieve, at the same time, a low latency and a high throughput. In particular, virtually all benchmarks measure throughput, or throughput-related figures of merit, but, for BFQ, they use the scheduler in its default configuration. This configuration is geared, instead, toward a low latency. This is evidently a sign that BFQ documentation is still too unclear on this important aspect. This commit addresses this issue by stressing how BFQ configuration must be (easily) changed if the only goal is maximum throughput. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-19block, bfq: improve responsivenessPaolo Valente1-0/+9
This patch introduces a simple heuristic to load applications quickly, and to perform the I/O requested by interactive applications just as quickly. To this purpose, both a newly-created queue and a queue associated with an interactive application (we explain in a moment how BFQ decides whether the associated application is interactive), receive the following two special treatments: 1) The weight of the queue is raised. 2) The queue unconditionally enjoys device idling when it empties; in fact, if the requests of a queue are sync, then performing device idling for the queue is a necessary condition to guarantee that the queue receives a fraction of the throughput proportional to its weight (see [1] for details). For brevity, we call just weight-raising the combination of these two preferential treatments. For a newly-created queue, weight-raising starts immediately and lasts for a time interval that: 1) depends on the device speed and type (rotational or non-rotational), and 2) is equal to the time needed to load (start up) a large-size application on that device, with cold caches and with no additional workload. Finally, as for guaranteeing a fast execution to interactive, I/O-related tasks (such as opening a file), consider that any interactive application blocks and waits for user input both after starting up and after executing some task. After a while, the user may trigger new operations, after which the application stops again, and so on. Accordingly, the low-latency heuristic weight-raises again a queue in case it becomes backlogged after being idle for a sufficiently long (configurable) time. The weight-raising then lasts for the same time as for a just-created queue. According to our experiments, the combination of this low-latency heuristic and of the improvements described in the previous patch allows BFQ to guarantee a high application responsiveness. [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O Scheduler", Proceedings of the First Workshop on Mobile System Technologies (MST-2015), May 2015. http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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