1. 09 Jan, 2016 1 commit
  2. 11 Dec, 2015 1 commit
  3. 27 Sep, 2014 1 commit
  4. 19 May, 2014 3 commits
  5. 25 Oct, 2013 1 commit
    • Jens Axboe's avatar
      blk-mq: new multi-queue block IO queueing mechanism · 320ae51f
      Jens Axboe authored
      Linux currently has two models for block devices:
      
      - The classic request_fn based approach, where drivers use struct
        request units for IO. The block layer provides various helper
        functionalities to let drivers share code, things like tag
        management, timeout handling, queueing, etc.
      
      - The "stacked" approach, where a driver squeezes in between the
        block layer and IO submitter. Since this bypasses the IO stack,
        driver generally have to manage everything themselves.
      
      With drivers being written for new high IOPS devices, the classic
      request_fn based driver doesn't work well enough. The design dates
      back to when both SMP and high IOPS was rare. It has problems with
      scaling to bigger machines, and runs into scaling issues even on
      smaller machines when you have IOPS in the hundreds of thousands
      per device.
      
      The stacked approach is then most often selected as the model
      for the driver. But this means that everybody has to re-invent
      everything, and along with that we get all the problems again
      that the shared approach solved.
      
      This commit introduces blk-mq, block multi queue support. The
      design is centered around per-cpu queues for queueing IO, which
      then funnel down into x number of hardware submission queues.
      We might have a 1:1 mapping between the two, or it might be
      an N:M mapping. That all depends on what the hardware supports.
      
      blk-mq provides various helper functions, which include:
      
      - Scalable support for request tagging. Most devices need to
        be able to uniquely identify a request both in the driver and
        to the hardware. The tagging uses per-cpu caches for freed
        tags, to enable cache hot reuse.
      
      - Timeout handling without tracking request on a per-device
        basis. Basically the driver should be able to get a notification,
        if a request happens to fail.
      
      - Optional support for non 1:1 mappings between issue and
        submission queues. blk-mq can redirect IO completions to the
        desired location.
      
      - Support for per-request payloads. Drivers almost always need
        to associate a request structure with some driver private
        command structure. Drivers can tell blk-mq this at init time,
        and then any request handed to the driver will have the
        required size of memory associated with it.
      
      - Support for merging of IO, and plugging. The stacked model
        gets neither of these. Even for high IOPS devices, merging
        sequential IO reduces per-command overhead and thus
        increases bandwidth.
      
      For now, this is provided as a potential 3rd queueing model, with
      the hope being that, as it matures, it can replace both the classic
      and stacked model. That would get us back to having just 1 real
      model for block devices, leaving the stacked approach to dm/md
      devices (as it was originally intended).
      
      Contributions in this patch from the following people:
      
      Shaohua Li <shli@fusionio.com>
      Alexander Gordeev <agordeev@redhat.com>
      Christoph Hellwig <hch@infradead.org>
      Mike Christie <michaelc@cs.wisc.edu>
      Matias Bjorling <m@bjorling.me>
      Jeff Moyer <jmoyer@redhat.com>
      Acked-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      320ae51f
  6. 30 Sep, 2013 1 commit
    • Paul Gortmaker's avatar
      block: change config option name for cmdline partition parsing · 080506ad
      Paul Gortmaker authored
      Recently commit bab55417 ("block: support embedded device command
      line partition") introduced CONFIG_CMDLINE_PARSER.  However, that name
      is too generic and sounds like it enables/disables generic kernel boot
      arg processing, when it really is block specific.
      
      Before this option becomes a part of a full/final release, add the BLK_
      prefix to it so that it is clear in absence of any other context that it
      is block specific.
      
      In addition, fix up the following less critical items:
       - help text was not really at all helpful.
       - index file for Documentation was not updated
       - add the new arg to Documentation/kernel-parameters.txt
       - clarify wording in source comments
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Cai Zhiyong <caizhiyong@huawei.com>
      Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      080506ad
  7. 11 Sep, 2013 1 commit
    • Cai Zhiyong's avatar
      block: support embedded device command line partition · bab55417
      Cai Zhiyong authored
      Read block device partition table from command line.  The partition used
      for fixed block device (eMMC) embedded device.  It is no MBR, save
      storage space.  Bootloader can be easily accessed by absolute address of
      data on the block device.  Users can easily change the partition.
      
      This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
      About the partition verbose reference
      "Documentation/block/cmdline-partition.txt"
      
      [akpm@linux-foundation.org: fix printk text]
      [yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()]
      Signed-off-by: default avatarCai Zhiyong <caizhiyong@huawei.com>
      Cc: Karel Zak <kzak@redhat.com>
      Cc: "Wanglin (Albert)" <albert.wanglin@huawei.com>
      Cc: Marius Groeger <mag@sysgo.de>
      Cc: David Woodhouse <dwmw2@infradead.org>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Brian Norris <computersforpeace@gmail.com>
      Cc: Artem Bityutskiy <dedekind@infradead.org>
      Signed-off-by: default avatarWei Yongjun <yongjun_wei@trendmicro.com.cn>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bab55417
  8. 03 Jan, 2012 2 commits
  9. 31 Jul, 2011 1 commit
    • Mike Christie's avatar
      block: add bsg helper library · aa387cc8
      Mike Christie authored
      This moves the FC classes bsg code to the block layer and
      makes it a lib so that other classes like iscsi and SAS can use it.
      
      It is helpful because working with the request queue, bios,
      creating scatterlists, etc are a pain that the LLD does not
      have to worry about with normal IOs and should not have to
      worry about for bsg requests.
      Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      aa387cc8
  10. 16 Sep, 2010 1 commit
  11. 10 Sep, 2010 1 commit
  12. 28 Apr, 2010 1 commit
  13. 03 Dec, 2009 1 commit
  14. 03 Oct, 2009 1 commit
  15. 11 Sep, 2009 1 commit
    • Jens Axboe's avatar
      block: add blk-iopoll, a NAPI like approach for block devices · 5e605b64
      Jens Axboe authored
      This borrows some code from NAPI and implements a polled completion
      mode for block devices. The idea is the same as NAPI - instead of
      doing the command completion when the irq occurs, schedule a dedicated
      softirq in the hopes that we will complete more IO when the iopoll
      handler is invoked. Devices have a budget of commands assigned, and will
      stay in polled mode as long as they continue to consume their budget
      from the iopoll softirq handler. If they do not, the device is set back
      to interrupt completion mode.
      
      This patch holds the core bits for blk-iopoll, device driver support
      sold separately.
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      5e605b64
  16. 01 Jul, 2009 1 commit
    • Jens Axboe's avatar
      block: get rid of queue-private command filter · 018e0446
      Jens Axboe authored
      The initial patches to support this through sysfs export were broken
      and have been if 0'ed out in any release. So lets just kill the code
      and reclaim some space in struct request_queue, if anyone would later
      like to fixup the sysfs bits, the git history can easily restore
      the removed bits.
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      018e0446
  17. 09 Feb, 2009 1 commit
  18. 09 Oct, 2008 2 commits
  19. 03 Jul, 2008 2 commits
  20. 29 Jan, 2008 4 commits
  21. 12 Oct, 2007 1 commit
  22. 10 Oct, 2007 1 commit
  23. 16 Jul, 2007 1 commit
  24. 30 Sep, 2006 1 commit
    • David Howells's avatar
      [PATCH] BLOCK: Make it possible to disable the block layer [try #6] · 9361401e
      David Howells authored
      Make it possible to disable the block layer.  Not all embedded devices require
      it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
      the block layer to be present.
      
      This patch does the following:
      
       (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
           support.
      
       (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
           an item that uses the block layer.  This includes:
      
           (*) Block I/O tracing.
      
           (*) Disk partition code.
      
           (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
      
           (*) The SCSI layer.  As far as I can tell, even SCSI chardevs use the
           	 block layer to do scheduling.  Some drivers that use SCSI facilities -
           	 such as USB storage - end up disabled indirectly from this.
      
           (*) Various block-based device drivers, such as IDE and the old CDROM
           	 drivers.
      
           (*) MTD blockdev handling and FTL.
      
           (*) JFFS - which uses set_bdev_super(), something it could avoid doing by
           	 taking a leaf out of JFFS2's book.
      
       (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
           linux/elevator.h contingent on CONFIG_BLOCK being set.  sector_div() is,
           however, still used in places, and so is still available.
      
       (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
           parts of linux/fs.h.
      
       (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
      
       (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
      
       (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
           is not enabled.
      
       (*) fs/no-block.c is created to hold out-of-line stubs and things that are
           required when CONFIG_BLOCK is not set:
      
           (*) Default blockdev file operations (to give error ENODEV on opening).
      
       (*) Makes some /proc changes:
      
           (*) /proc/devices does not list any blockdevs.
      
           (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
      
       (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
      
       (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
           given command other than Q_SYNC or if a special device is specified.
      
       (*) In init/do_mounts.c, no reference is made to the blockdev routines if
           CONFIG_BLOCK is not defined.  This does not prohibit NFS roots or JFFS2.
      
       (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
           error ENOSYS by way of cond_syscall if so).
      
       (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
           CONFIG_BLOCK is not set, since they can't then happen.
      Signed-Off-By: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      9361401e
  25. 23 Mar, 2006 1 commit
  26. 04 Nov, 2005 1 commit