Messages in this thread | | | Subject | Re: [PATCH 3/3] mm/memcg: Unify swap and memsw page counters | From | Waiman Long <> | Date | Mon, 24 Aug 2020 12:02:48 -0400 |
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On 8/20/20 11:46 AM, Shakeel Butt wrote: > On Thu, Aug 20, 2020 at 6:04 AM Waiman Long <longman@redhat.com> wrote: >> The swap page counter is v2 only while memsw is v1 only. As v1 and v2 >> controllers cannot be active at the same time, there is no point to keep >> both swap and memsw page counters in mem_cgroup. The previous patch has >> made sure that memsw page counter is updated and accessed only when in >> v1 code paths. So it is now safe to alias the v1 memsw page counter to v2 >> swap page counter. This saves 14 long's in the size of mem_cgroup. This >> is a saving of 112 bytes for 64-bit archs. >> >> Signed-off-by: Waiman Long <longman@redhat.com> >> --- >> include/linux/memcontrol.h | 3 +-- >> mm/memcontrol.c | 8 +++++--- >> 2 files changed, 6 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> index d0b036123c6a..d2a819d7db70 100644 >> --- a/include/linux/memcontrol.h >> +++ b/include/linux/memcontrol.h >> @@ -216,10 +216,9 @@ struct mem_cgroup { >> >> /* Accounted resources */ >> struct page_counter memory; >> - struct page_counter swap; >> + struct page_counter swap; /* memsw (memory+swap) for v1 */ >> >> /* Legacy consumer-oriented counters */ >> - struct page_counter memsw; >> struct page_counter kmem; >> struct page_counter tcpmem; >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index d219dca5239f..04c3794cdc98 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -68,6 +68,11 @@ >> >> #include <trace/events/vmscan.h> >> >> +/* >> + * The v1 memsw page counter is aliased to the v2 swap page counter. >> + */ >> +#define memsw swap >> + > Personally I would prefer a union instead of #define.
Yes, that is also what I am thinking about in the v2.
Cheers, Longman
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