Re: [PATCH v3 1/8] memcg: reduce memory size of mem_cgroup_events_index

[T.J. Mercier]

On Tue, Apr 30, 2024 at 1:34 AM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote:
>
> On Mon, Apr 29, 2024 at 11:06 PM Shakeel Butt <shakeel.butt@linuxdev> wrote:
> >
> > mem_cgroup_events_index is a translation table to get the right index of
> > the memcg relevant entry for the general vm_event_item. At the moment,
> > it is defined as integer array. However on a typical system the max
> > entry of vm_event_item (NR_VM_EVENT_ITEMS) is 113, so we don't need to
> > use int as storage type of the array. For now just use int8_t as type
> > and add a BUILD_BUG_ON() and will switch to short once NR_VM_EVENT_ITEMS
> > touches 127.
> >
> > Another benefit of this change is that the translation table fits in 2
> > cachelines while previously it would require 8 cachelines (assuming 64
> > bytes cachesline).
> >
> > Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
> > Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
>
> Reviewed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
>
Reviewed-by: T.J. Mercier <tjmercier@xxxxxxxxxx>