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* [PATCHSET btrfs/for-next] btrfs: fix cgroup writeback support
@ 2019-06-14  0:33 Tejun Heo
  2019-06-14  0:33 ` [PATCH 1/8] blkcg, writeback: Add wbc->no_wbc_acct Tejun Heo
                   ` (8 more replies)
  0 siblings, 9 replies; 21+ messages in thread
From: Tejun Heo @ 2019-06-14  0:33 UTC (permalink / raw)
  To: dsterba, clm, josef, axboe, jack
  Cc: linux-btrfs, linux-kernel, linux-block, kernel-team

Hello,

When writeback is executed asynchronously (e.g. for compression), bios
are bounced to and issued by worker pool shared by all cgroups.  This
leads to significant priority inversions when cgroup IO control is in
use - IOs for a low priority cgroup can tie down the workers forcing
higher priority IOs to wait behind them.

This patchset adds an bio punt mechanism to blkcg.  A bio tagged with
REQ_CGROUP_PUNT flag is bounced to the asynchronous issue context of
the associated blkcg on bio_submit().  As the bios are issued from
per-blkcg work items, there's no concern for priority inversions and
it doesn't require invasive changes to the filesystems.  The mechanism
should be generally useful for IO control support across different
filesystems.

btrfs async path is simplified and is updated to use REQ_CGROUP_PUNT
for submitting asynchronous bios.  It's also updated to always and
only account the original writeback bios against wbc so that cgroup
inode writeback ownership arbitration isn't confused by downstream
bios.

This patchset contains the following 8 patches.  The first three are
my blkcg patches to implement the needed mechanisms.  The latter five
are Chris Mason's btrfs cleanup and update patches.  Please let me
know how the patches should be routed.  Given that there currently
aren't other users, it's likely the easiest to route all through btrfs
tree.

 0001-blkcg-writeback-Add-wbc-no_wbc_acct.patch
 0002-blkcg-writeback-Implement-wbc_blkcg_css.patch
 0003-blkcg-implement-REQ_CGROUP_PUNT.patch
 0004-Btrfs-stop-using-btrfs_schedule_bio.patch
 0005-Btrfs-delete-the-entire-async-bio-submission-framewo.patch
 0006-Btrfs-only-associate-the-locked-page-with-one-async_.patch
 0007-Btrfs-use-REQ_CGROUP_PUNT-for-worker-thread-submitte.patch
 0008-Btrfs-extent_write_locked_range-should-attach-inode-.patch

0001-0003 implement wbc->no_wbc_acct, wbc_blkcg_css() and
REQ_CGROUP_PUNT.

0004-0006 are prep patches to simplify / improve async bio submission.

0007 makes btrfs use REQ_CGROUP_PUNT for async bios.

0008 fixes wbc writeback accounting for IOs issued through
extent_write_locked_range().

This patchset is also available in the following git branch.

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-btrfs-cgroup-updates

Thanks, diffstat follows.

 block/blk-cgroup.c          |   54 +++++++++
 block/blk-core.c            |    3 
 fs/btrfs/compression.c      |   16 +-
 fs/btrfs/compression.h      |    3 
 fs/btrfs/ctree.h            |    1 
 fs/btrfs/disk-io.c          |   25 +---
 fs/btrfs/extent_io.c        |   15 +-
 fs/btrfs/inode.c            |   61 ++++++++--
 fs/btrfs/super.c            |    1 
 fs/btrfs/volumes.c          |  264 --------------------------------------------
 fs/btrfs/volumes.h          |   10 -
 fs/fs-writeback.c           |    2 
 include/linux/backing-dev.h |    1 
 include/linux/blk-cgroup.h  |   16 ++
 include/linux/blk_types.h   |   10 +
 include/linux/writeback.h   |   24 +++-
 16 files changed, 194 insertions(+), 312 deletions(-)

--
tejun


^ permalink raw reply	[flat|nested] 21+ messages in thread

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Thread overview: 21+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-14  0:33 [PATCHSET btrfs/for-next] btrfs: fix cgroup writeback support Tejun Heo
2019-06-14  0:33 ` [PATCH 1/8] blkcg, writeback: Add wbc->no_wbc_acct Tejun Heo
2019-06-14 13:41   ` Josef Bacik
2019-06-14  0:33 ` [PATCH 2/8] blkcg, writeback: Implement wbc_blkcg_css() Tejun Heo
2019-06-14 13:41   ` Josef Bacik
2019-06-14  0:33 ` [PATCH 3/8] blkcg: implement REQ_CGROUP_PUNT Tejun Heo
2019-06-14 13:43   ` Josef Bacik
2019-06-14  0:33 ` [PATCH 4/8] Btrfs: stop using btrfs_schedule_bio() Tejun Heo
2019-06-14 13:45   ` Josef Bacik
2019-06-14  0:33 ` [PATCH 5/8] Btrfs: delete the entire async bio submission framework Tejun Heo
2019-06-14 13:48   ` Josef Bacik
2019-06-14  0:33 ` [PATCH 6/8] Btrfs: only associate the locked page with one async_cow struct Tejun Heo
2019-06-14 13:48   ` Josef Bacik
2019-06-14  0:33 ` [PATCH 7/8] Btrfs: use REQ_CGROUP_PUNT for worker thread submitted bios Tejun Heo
2019-06-14 13:50   ` Josef Bacik
2019-06-14 15:15   ` David Sterba
2019-06-14 15:34     ` Tejun Heo
2019-06-14  0:33 ` [PATCH 8/8] Btrfs: extent_write_locked_range() should attach inode->i_wb Tejun Heo
2019-06-14 14:12   ` Josef Bacik
2019-06-14 15:32   ` [PATCH v2 " Tejun Heo
2019-06-14 17:46 ` [PATCHSET btrfs/for-next] btrfs: fix cgroup writeback support Tejun Heo

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