On 8/26/19 10:06 AM, Tejun Heo wrote: > Hello, > > Changes from v1[1]: > > * More comments explaining the parameters. > > * 0003-writeback-Separate-out-wb_get_lookup-from-wb_get_create.patch > added and avoid spuriously creating missing wbs for foreign > flushing. > > Changes from v2[2]: > > * Added livelock avoidance and applied other smaller changes suggested > by Jan. > > There's an inherent mismatch between memcg and writeback. The former > trackes ownership per-page while the latter per-inode. This was a > deliberate design decision because honoring per-page ownership in the > writeback path is complicated, may lead to higher CPU and IO overheads > and deemed unnecessary given that write-sharing an inode across > different cgroups isn't a common use-case. > > Combined with inode majority-writer ownership switching, this works > well enough in most cases but there are some pathological cases. For > example, let's say there are two cgroups A and B which keep writing to > different but confined parts of the same inode. B owns the inode and > A's memory is limited far below B's. A's dirty ratio can rise enough > to trigger balance_dirty_pages() sleeps but B's can be low enough to > avoid triggering background writeback. A will be slowed down without > a way to make writeback of the dirty pages happen. > > This patchset implements foreign dirty recording and foreign mechanism > so that when a memcg encounters a condition as above it can trigger > flushes on bdi_writebacks which can clean its pages. Please see the > last patch for more details. > > This patchset contains the following four patches. > > 0001-writeback-Generalize-and-expose-wb_completion.patch > 0002-bdi-Add-bdi-id.patch > 0003-writeback-Separate-out-wb_get_lookup-from-wb_get_create.patch > 0004-writeback-memcg-Implement-cgroup_writeback_by_id.patch > 0005-writeback-memcg-Implement-foreign-dirty-flushing.patch > > 0001-0004 are prep patches which expose wb_completion and implement > bdi->id and flushing by bdi and memcg IDs. > > 0005 implements foreign inode flushing. > > Thanks. diffstat follows. > > fs/fs-writeback.c | 130 ++++++++++++++++++++++++++++--------- > include/linux/backing-dev-defs.h | 23 ++++++ > include/linux/backing-dev.h | 5 + > include/linux/memcontrol.h | 39 +++++++++++ > include/linux/writeback.h | 2 > mm/backing-dev.c | 120 +++++++++++++++++++++++++++++----- > mm/memcontrol.c | 134 +++++++++++++++++++++++++++++++++++++++ > mm/page-writeback.c | 4 + > 8 files changed, 404 insertions(+), 53 deletions(-) Applied for 5.4, thanks Tejun. -- Jens Axboe
