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* blkcg: implement per-blkg request allocationTejun Heo2012-06-271-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, request_queue has one request_list to allocate requests from regardless of blkcg of the IO being issued. When the unified request pool is used up, cfq proportional IO limits become meaningless - whoever grabs the next request being freed wins the race regardless of the configured weights. This can be easily demonstrated by creating a blkio cgroup w/ very low weight, put a program which can issue a lot of random direct IOs there and running a sequential IO from a different cgroup. As soon as the request pool is used up, the sequential IO bandwidth crashes. This patch implements per-blkg request_list. Each blkg has its own request_list and any IO allocates its request from the matching blkg making blkcgs completely isolated in terms of request allocation. * Root blkcg uses the request_list embedded in each request_queue, which was renamed to @q->root_rl from @q->rq. While making blkcg rl handling a bit harier, this enables avoiding most overhead for root blkcg. * Queue fullness is properly per request_list but bdi isn't blkcg aware yet, so congestion state currently just follows the root blkcg. As writeback isn't aware of blkcg yet, this works okay for async congestion but readahead may get the wrong signals. It's better than blkcg completely collapsing with shared request_list but needs to be improved with future changes. * After this change, each block cgroup gets a full request pool making resource consumption of each cgroup higher. This makes allowing non-root users to create cgroups less desirable; however, note that allowing non-root users to directly manage cgroups is already severely broken regardless of this patch - each block cgroup consumes kernel memory and skews IO weight (IO weights are not hierarchical). v2: queue-sysfs.txt updated and patch description udpated as suggested by Vivek. v3: blk_get_rl() wasn't checking error return from blkg_lookup_create() and may cause oops on lookup failure. Fix it by falling back to root_rl on blkg lookup failures. This problem was spotted by Rakesh Iyer <rni@google.com>. v4: Updated to accomodate 458f27a982 "block: Avoid missed wakeup in request waitqueue". blk_drain_queue() now wakes up waiters on all blkg->rl on the target queue. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Documentation: drop as block elevator reference in switching-sched.txtWang Sheng-Hui2011-11-041-2/+2
| | | | | | | | | | Remove 'as' for as is no longer supported, and we can not use 'elevator=as' any more. Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com> Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* doc: fix broken referencesPaul Bolle2011-09-271-1/+1
| | | | | | | | | | | | | There are numerous broken references to Documentation files (in other Documentation files, in comments, etc.). These broken references are caused by typo's in the references, and by renames or removals of the Documentation files. Some broken references are simply odd. Fix these broken references, sometimes by dropping the irrelevant text they were part of. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* cfq-iosched: Add documentation about idlingVivek Goyal2011-08-051-0/+71
| | | | | | | | | | | | | | | | | There are always questions about why CFQ is idling on various conditions. Recent ones is Christoph asking again why to idle on REQ_NOIDLE. His assertion is that XFS is relying more and more on workqueues and is concerned that CFQ idling on IO from every workqueue will impact XFS badly. So he suggested that I add some more documentation about CFQ idling and that can provide more clarity on the topic and also gives an opprotunity to poke a hole in theory and lead to improvements. So here is my attempt at that. Any comments are welcome. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: strict rq_affinityDan Williams2011-07-231-3/+7
| | | | | | | | | | | | | | | | | | | | | Some systems benefit from completions always being steered to the strict requester cpu rather than the looser "per-socket" steering that blk_cpu_to_group() attempts by default. This is because the first CPU in the group mask ends up being completely overloaded with work, while the others (including the original submitter) has power left to spare. Allow the strict mode to be set by writing '2' to the sysfs control file. This is identical to the scheme used for the nomerges file, where '2' is a more aggressive setting than just being turned on. echo 2 > /sys/block/<bdev>/queue/rq_affinity Cc: Christoph Hellwig <hch@infradead.org> Cc: Roland Dreier <roland@purestorage.com> Tested-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* Fix common misspellingsLucas De Marchi2011-03-311-2/+2
| | | | | | Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
* block: remove per-queue pluggingJens Axboe2011-03-101-5/+0
| | | | | | | | Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* Documentation: remove anticipatory scheduler infoRandy Dunlap2010-11-111-4/+4
| | | | | | | | | | Remove anticipatory block I/O scheduler info from Documentation/ since the code has been deleted. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Reported-by: "Robert P. J. Day" <rpjday@crashcourse.ca> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* Merge branch 'v2.6.36-rc8' into for-2.6.37/barrierJens Axboe2010-10-191-0/+45
|\ | | | | | | | | | | | | | | | | Conflicts: block/blk-core.c drivers/block/loop.c mm/swapfile.c Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq-iosched: Documentation help for new tunablesVivek Goyal2010-08-231-0/+45
| | | | | | | | | | | | | | | | Some documentation to provide help with tunables. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | block: update documentation for REQ_FLUSH / REQ_FUAChristoph Hellwig2010-09-103-263/+88
|/ | | | | | Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* nick piggin: change email addressNick Piggin2010-08-051-1/+1
| | | | | Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Documentation: fix block/biodoc.txt dma mapping descriptionFUJITA Tomonori2010-03-081-2/+2
| | | | | | | | | | | - It looks incorrect to use blk_rq_map_sg with pci_map_page here about DMA mappings. dma_map_sg? - better to use dma_map_page instead of pci_map_page. http://marc.info/?l=linux-kernel&m=126596737604808&w=2 Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Merge branch 'master' into for-2.6.34Jens Axboe2010-02-221-1/+1
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| * Documentation: Rename Documentation/DMA-mapping.txtKusanagi Kouichi2010-01-021-1/+1
| | | | | | | | | | | | | | | | | | It seems that Documentation/DMA-mapping.txt was supposed to be renamed to Documentation/PCI/PCI-DMA-mapping.txt. Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | block: Added in stricter no merge semantics for block I/OAlan D. Brunelle2010-01-291-5/+5
|/ | | | | | | | | | | | | | | | | Updated 'nomerges' tunable to accept a value of '2' - indicating that _no_ merges at all are to be attempted (not even the simple one-hit cache). The following table illustrates the additional benefit - 5 minute runs of a random I/O load were applied to a dozen devices on a 16-way x86_64 system. nomerges Throughput %System Improvement (tput / %sys) -------- ------------ ----------- ------------------------- 0 12.45 MB/sec 0.669365609 1 12.50 MB/sec 0.641519199 0.40% / 2.71% 2 12.52 MB/sec 0.639849750 0.56% / 2.96% Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: remove Documentation/block/as-iosched.txtFUJITA Tomonori2009-12-182-174/+0
| | | | | | | | Commit 492af6350a5ccf087e4964104a276ed358811458 removed the AS IO scheduler, so remove its documentation too. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Trivial typo fixes in Documentation/block/data-integrity.txt.Andre Noll2009-07-011-2/+2
| | | | | | Signed-off-by: Andre Noll <maan@systemlinux.org> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* trivial: Miscellaneous documentation typo fixesMatt LaPlante2009-06-121-1/+1
| | | | | | | Fix various typos in documentation txts. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* Removed reference to non-existing file Documentation/PCI/PCI-DMA-mapping.txtvibi sreenivasan2009-06-021-1/+1
| | | | | | | | File Documentation/PCI/PCI-DMA-mapping.txt does not exist. Documentation/DMA-mapping.txt contains DMA Mapping details Signed-off-by: vibi sreenivasan <vibi_sreenivasan@cms.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: update biodoc.txt on pluggingJens Axboe2009-04-151-13/+6
| | | | | | | We do per-device plugging, get rid of any references to tq_disk as that has been dead since 2.6.5 or so. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: Repeated lines in switching-sched.txtAvishay Traeger2009-03-261-6/+0
| | | | | | | These lines appear in this file twice - removed one occurrence. Signed-off-by: Avishay Traeger <avishay@il.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add text file detailing queue/ sysfs filesJens Axboe2009-02-021-0/+63
| | | | Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Mark mandatory elevator functions in the biodoc.txtNikanth Karthikesan2009-01-301-3/+3
| | | | | | | | | biodoc.txt mentions that elevator functions marked with * are mandatory, but no function is marked with *. Mark the 3 functions which should be implemented by any io scheduler. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Documentation: move DMA-mapping.txt to Doc/PCI/Randy Dunlap2009-01-301-2/+3
| | | | | | | | | | | | | | | Move DMA-mapping.txt to Documentation/PCI/. DMA-mapping.txt was supposed to be moved from Documentation/ to Documentation/PCI/. The 00-INDEX files in those two directories were updated, along with a few other text files, but the file itself somehow escaped being moved, so move it and update more text files and source files with its new location. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> cc: Jesse Barnes <jbarnes@virtuousgeek.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Documentation: remove reference to ll_rw_blk.c and moved ↵Nikanth Karthikesan2008-12-291-3/+3
| | | | | | | | | | | drivers/block/elevator.c The drivers/block/ll_rw_block.c has been split and organized in the block/ directory, and also drivers/block/elevator.c has been moved to the block/ directory. Update Documentation/block/biodoc.txt accordingly Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Merge branch 'docs' of git://git.lwn.net/linux-2.6Linus Torvalds2008-10-161-2/+2
|\ | | | | | | | | | | | | | | | | | | | | * 'docs' of git://git.lwn.net/linux-2.6: Document panic_on_unrecovered_nmi sysctl Add a reference to paper to SubmittingPatches Add kerneldoc documentation for new printk format extensions Remove videobook.tmpl doc: Test-by? Add the development process document Documentation/block/data-integrity.txt: Fix section numbers
| * Documentation/block/data-integrity.txt: Fix section numbersAlberto Bertogli2008-10-161-2/+2
| | | | | | | | | | Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | block: update documentation for deadline fifo_batch tunableAaron Carroll2008-10-091-4/+10
|/ | | | | | | | Update the description of fifo_batch to match the current implementation, and include a description of how to tune it. Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: Data integrity infrastructure documentationMartin K. Petersen2008-07-031-0/+327
| | | | | Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* DOCUMENTATION: Use newer DEFINE_SPINLOCK macro in docs.Robert P. J. Day2008-04-221-1/+1
| | | | | Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
* Add Documentation/block/00-INDEXRob Landley2007-10-161-0/+20
| | | | | | | Add Documentation/block/00-INDEX Signed-off-by: Rob Landley <rob@landley.net> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Some IO scheduler cleanup in Documentation/blockAlan D. Brunelle2007-10-163-24/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | as-iosched.txt: o Changed IO scheduler selection text to a reference to the switching-sched.txt file. o Fixed typo: 'for up time...' -> 'for up to...' o Added short description of the est_time file. deadline-iosched.txt: o Changed IO scheduler selection text to a reference to the switching-sched.txt file. o Removed references to non-existent seek-cost and stream_unit. o Fixed typo: 'write_starved' -> 'writes_starved' switching-sched.txt: o Added in boot-time argument to set the default IO scheduler. (From as-iosched.txt) o Added in sysfs mount instructions. (From deadline-iosched.txt) Signed-off-by: Alan D. Brunelle <Alan.Brunelle@hp.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Update Jens Axboe's email in Documentation/*Rob Landley2007-10-164-5/+5
| | | | | | | Jens Axboe's old email address bounces. Signed-off-by: Rob Landley <rob@landley.net> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Corrections in Documentation/block/ioprio.txtDhaval Giani2007-10-101-2/+9
| | | | | | | | | The newer glibc does not allow system calls to be made via _syscallN() wrapper. They have to be made through syscall(). The ionice code used the older interface. Correcting it to use syscall. Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Introduce rq_for_each_segment replacing rq_for_each_bioNeilBrown2007-10-101-10/+10
| | | | | | | | | | | | | | | Every usage of rq_for_each_bio wraps a usage of bio_for_each_segment, so these can be combined into rq_for_each_segment. We define "struct req_iterator" to hold the 'bio' and 'index' that are needed for the double iteration. Signed-off-by: Neil Brown <neilb@suse.de> Various compile fixes by me... Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [BLOCK] Get rid of request_queue_t typedefJens Axboe2007-07-243-9/+9
| | | | | | | | | Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Documentation/block/barrier.txt is not in sync with the actual code: - ↵Geert Uytterhoeven2007-07-101-13/+3
| | | | | | | | | blk_queue_ordered() no longer has a gfp_mask parameter - blk_queue_ordered_locked() no longer exists - sd_prepare_flush() looks slightly different Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Acked-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* genhd: expose AN to user spaceKristen Carlson Accardi2007-05-241-0/+15
| | | | | | | | | | | | Allow user space to determine if a disk supports Asynchronous Notification of media changes. This is done by adding a new sysfs file "capability_flags", which is documented in (insert file name). This sysfs file will export all disk capabilities flags to user space. We also define a new flag to define the media change notification capability. Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* misc doc and kconfig typosMatt LaPlante2007-05-091-4/+4
| | | | | | | Fix various typos in kernel docs and Kconfigs, 2.6.21-rc4. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [PATCH] block: document io scheduler allow_merge_fn hookJens Axboe2006-12-201-0/+7
| | | | Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] io/storage: Documentation update to as-iosched.txtFilipe2006-12-071-2/+4
| | | | | | | | | | Documentation update, adding references to CFQ scheduler and to another document about selecting IO Schedulers. Signed-off-by: Filipe Lautert <filipe@icewall.org> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Fix typos in /Documentation : MiscMatt LaPlante2006-11-301-2/+2
| | | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some misc words. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fix typos in /Documentation : 'U-Z'Matt LaPlante2006-11-301-3/+3
| | | | | | | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some +words starting with the letters 'U-Z'. Looks like I made it through the alphabet...just in time to start over again +too! Maybe I can fit more profound fixes into the next round...? Time will +tell. :) Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Documentation: remove duplicated wordsPaolo Ornati2006-10-031-1/+1
| | | | | | | | | | | | | | | Remove many duplicated words under Documentation/ and do other small cleanups. Examples: "and and" --> "and" "in in" --> "in" "the the" --> "the" "the the" --> "to the" ... Signed-off-by: Paolo Ornati <ornati@fastwebnet.it> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fix typos in Documentation/: 'S'Matt LaPlante2006-10-031-2/+2
| | | | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some words starting with the letter 'S'. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Alan Cox <alan@redhat.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fix typos in Documentation/: 'Q'-'R'Matt LaPlante2006-10-031-1/+1
| | | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some words starting with the letters 'Q'-'R'. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fix typos in Documentation/: 'N'-'P'Matt LaPlante2006-10-032-3/+3
| | | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some words starting with the letters 'N'-'P'. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fix typos in Documentation/: 'H'-'M'Matt LaPlante2006-10-031-1/+1
| | | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some words starting with the letters 'H'-'M'. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fix typos in Documentation/: 'F'-'G'Matt LaPlante2006-10-032-2/+2
| | | | | | | | This patch fixes typos in various Documentation txts. The patch addresses some words starting with the letters 'F'-'G'. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Signed-off-by: Adrian Bunk <bunk@stusta.de>
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