On Wed, Mar 10, 2021 at 1:41 PM Yang Shi [off-list ref] wrote:

On Wed, Mar 10, 2021 at 1:08 PM Shakeel Butt [off-list ref] wrote:

quoted

On Wed, Mar 10, 2021 at 10:54 AM Yang Shi [off-list ref] wrote:

quoted

On Wed, Mar 10, 2021 at 10:24 AM Shakeel Butt [off-list ref] wrote:

quoted

On Wed, Mar 10, 2021 at 9:46 AM Yang Shi [off-list ref] wrote:

quoted

The number of deferred objects might get windup to an absurd number, and it
results in clamp of slab objects.  It is undesirable for sustaining workingset.

So shrink deferred objects proportional to priority and cap nr_deferred to twice
of cache items.

The idea is borrowed from Dave Chinner's patch:
https://lore.kernel.org/linux-xfs/20191031234618.15403-13-david@fromorbit.com/ (local)

Tested with kernel build and vfs metadata heavy workload in our production
environment, no regression is spotted so far.

Did you run both of these workloads in the same cgroup or separate cgroups?

Both are covered.

Have you tried just this patch i.e. without the first 12 patches?

No. It could be applied without the first 12 patches, but I didn't
test this combination specifically since I don't think it would have
any difference from with the first 12 patches. I tested running the
test case under root memcg, it seems equal to w/o the first 12 patches
and the only difference is where to get nr_deferred.

I am trying to measure the impact of this patch independently. One
point I can think of is the global reclaim. The first 12 patches do
not aim to improve the global reclaim but this patch will. I am just
wondering what would be negative if any of this patch.