| Message ID | 20190613223041.606735-6-tj@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] blk-iolatency: clear use_delay when io.latency is set to zero | expand |
On Thu 13-06-19 15:30:41, Tejun Heo wrote: > wbc_account_io() collects information on cgroup ownership of writeback > pages to determine which cgroup should own the inode. Pages can stay > associated with dead memcgs but we want to avoid attributing IOs to > dead blkcgs as much as possible as the association is likely to be > stale. However, currently, pages associated with dead memcgs > contribute to the accounting delaying and/or confusing the > arbitration. > > Fix it by ignoring pages associated with dead memcgs. > > Signed-off-by: Tejun Heo <tj@kernel.org> > Cc: Jan Kara <jack@suse.cz> I see Jens has already pulled the changes so this is mostly informative but the patch looks good to me. Honza > --- > fs/fs-writeback.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index e41cbe8e81b9..9ebfb1b28430 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -715,6 +715,7 @@ void wbc_detach_inode(struct writeback_control *wbc) > void wbc_account_io(struct writeback_control *wbc, struct page *page, > size_t bytes) > { > + struct cgroup_subsys_state *css; > int id; > > /* > @@ -726,7 +727,12 @@ void wbc_account_io(struct writeback_control *wbc, struct page *page, > if (!wbc->wb) > return; > > - id = mem_cgroup_css_from_page(page)->id; > + css = mem_cgroup_css_from_page(page); > + /* dead cgroups shouldn't contribute to inode ownership arbitration */ > + if (!(css->flags & CSS_ONLINE)) > + return; > + > + id = css->id; > > if (id == wbc->wb_id) { > wbc->wb_bytes += bytes; > -- > 2.17.1 >
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index e41cbe8e81b9..9ebfb1b28430 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -715,6 +715,7 @@ void wbc_detach_inode(struct writeback_control *wbc) void wbc_account_io(struct writeback_control *wbc, struct page *page, size_t bytes) { + struct cgroup_subsys_state *css; int id; /* @@ -726,7 +727,12 @@ void wbc_account_io(struct writeback_control *wbc, struct page *page, if (!wbc->wb) return; - id = mem_cgroup_css_from_page(page)->id; + css = mem_cgroup_css_from_page(page); + /* dead cgroups shouldn't contribute to inode ownership arbitration */ + if (!(css->flags & CSS_ONLINE)) + return; + + id = css->id; if (id == wbc->wb_id) { wbc->wb_bytes += bytes;
wbc_account_io() collects information on cgroup ownership of writeback pages to determine which cgroup should own the inode. Pages can stay associated with dead memcgs but we want to avoid attributing IOs to dead blkcgs as much as possible as the association is likely to be stale. However, currently, pages associated with dead memcgs contribute to the accounting delaying and/or confusing the arbitration. Fix it by ignoring pages associated with dead memcgs. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jan Kara <jack@suse.cz> --- fs/fs-writeback.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)