Hello,
The changes from the last take[L] are
* 0002-writeback-make-writeback_control-track-the-inode-bei.patch and
0003-writeback-implement-foreign-cgroup-inode-detection.patch
assumed that all wbc's are attached to the inode and wb being
written out; however, pageout() path doesn't participate in cgroup
writeback leading to oops.
pageout() isn't the main writeback path, so the impact on isolation
is relatively limited and as the whole path runs on the same thread
we don't want it to block on slow cgroups anyway. In the long term,
the best route seems to make the path kick off the usual writeback
path rather than trying to write pages directly.
Both patches updated to skip cgroup writeback related processing if
the wbc is not associated with inode / wb.
* might_lock() on tree_lock dropped from
0007-writeback-add-lockdep-annotation-to-inode_to_wb.patch due to
spurious locking context warnings. Unfortunately, there isn't a
simple way to express _irqsave for might_lock().
The previous two patchsets [1][2] implemented cgroup writeback support
and backpressure propagation through dirty throttling mechanism;
however, the inode is assigned to the wb (bdi_writeback) matching the
first dirtied page and stays there until released. This first-use
policy can easily lead to gross misbehaviors - a single stray dirty
page can cause gigatbytes to be written by the wrong cgroup. Also,
while concurrently write sharing an inode is extremely rare and
unsupported, inodes jumping cgroups over time are more common.
This patchset implements foreign cgroup inode detection and wb
switching. Each writeback run tracks the majority wb being written
using a simple but fairly robust algorithm and when an inode
persistently writes out more foreign cgroup pages than local ones, the
inode is transferred to the majority winner.
This patchset adds 8 bytes to inode making the total per-inode space
overhead of cgroup writeback support 16 bytes on 64bit systems. The
computational overhead should be negligible. If the writer changes
from one cgroup to another entirely, the mechanism can render the
correct switch verdict in several seconds of IO time in most cases and
it can converge on the correct answer in reasonable amount of time
even in more ambiguous cases.
This patchset contains the following 8 patches.
0001-writeback-relocate-wb-_try-_get-wb_put-inode_-attach.patch
0002-writeback-make-writeback_control-track-the-inode-bei.patch
0003-writeback-implement-foreign-cgroup-inode-detection.patch
0004-writeback-implement-locked_-inode_to_wb_and_lock_lis.patch
0005-writeback-implement-unlocked_inode_to_wb-transaction.patch
0006-writeback-use-unlocked_inode_to_wb-transaction-in-in.patch
0007-writeback-add-lockdep-annotation-to-inode_to_wb.patch
0008-writeback-implement-foreign-cgroup-inode-bdi_writeba.patch
0009-writeback-disassociate-inodes-from-dying-bdi_writeba.patch
This patchset is on top of
block/for-4.2/core b04a5636a665 ("block: replace trylock with mutex_lock in blkdev_reread_part()")
+ [1] [PATCHSET 1/3 v4 block/for-4.2/core] writeback: cgroup writeback support
+ [2] [PATCHSET 2/3 v3 block/for-4.2/core] writeback: cgroup writeback backpressure propagation
and available in the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup-writeback-switch-20150528
diffstat follows. Thanks.
fs/buffer.c | 26 -
fs/fs-writeback.c | 532 ++++++++++++++++++++++++++++++++++++++-
fs/mpage.c | 3
include/linux/backing-dev-defs.h | 66 ++++
include/linux/backing-dev.h | 142 ++++------
include/linux/fs.h | 11
include/linux/mm.h | 3
include/linux/writeback.h | 130 +++++++++
mm/backing-dev.c | 30 --
mm/filemap.c | 5
mm/page-writeback.c | 27 +
11 files changed, 836 insertions(+), 139 deletions(-)
--
tejun
[L] http://lkml.kernel.org/g/1432334183-6324-1-git-send-email-tj@xxxxxxxxxx
[1] http://lkml.kernel.org/g/1432329245-5844-1-git-send-email-tj@xxxxxxxxxx
[2] http://lkml.kernel.org/g/1428350674-8303-1-git-send-email-tj@xxxxxxxxxx
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