* Re: [RESEND PATCH 1/2 -mm] mm: account lazy free pages separately
2019-08-14 12:49 ` [RESEND PATCH 1/2 -mm] mm: account lazy free pages separately Vlastimil Babka
@ 2019-08-14 12:53 ` Michal Hocko
2019-08-15 4:53 ` Yang Shi
1 sibling, 0 replies; 3+ messages in thread
From: Michal Hocko @ 2019-08-14 12:53 UTC (permalink / raw)
To: Vlastimil Babka
Cc: Yang Shi, kirill.shutemov, hannes, rientjes, akpm, linux-mm,
linux-kernel, Linux API
On Wed 14-08-19 14:49:18, Vlastimil Babka wrote:
> On 8/9/19 8:26 PM, Yang Shi wrote:
> > Here the new counter is introduced for patch 2/2 to account deferred
> > split THPs into available memory since NR_ANON_THPS may contain
> > non-deferred split THPs.
> >
> > I could use an internal counter for deferred split THPs, but if it is
> > accounted by mod_node_page_state, why not just show it in /proc/meminfo?
>
> The answer to "Why not" is that it becomes part of userspace API (btw this
> patchset should have CC'd linux-api@ - please do for further iterations) and
> even if the implementation detail of deferred splitting might change in the
> future, we'll basically have to keep the counter (even with 0 value) in
> /proc/meminfo forever.
>
> Also, quite recently we have added the following counter:
>
> KReclaimable: Kernel allocations that the kernel will attempt to reclaim
> under memory pressure. Includes SReclaimable (below), and other
> direct allocations with a shrinker.
>
> Although THP allocations are not exactly "kernel allocations", once they are
> unmapped, they are in fact kernel-only, so IMHO it wouldn't be a big stretch to
> add the lazy THP pages there?
That would indeed fit in much better than a dedicated counter.
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RESEND PATCH 1/2 -mm] mm: account lazy free pages separately
2019-08-14 12:49 ` [RESEND PATCH 1/2 -mm] mm: account lazy free pages separately Vlastimil Babka
2019-08-14 12:53 ` Michal Hocko
@ 2019-08-15 4:53 ` Yang Shi
1 sibling, 0 replies; 3+ messages in thread
From: Yang Shi @ 2019-08-15 4:53 UTC (permalink / raw)
To: Vlastimil Babka, Michal Hocko
Cc: kirill.shutemov, hannes, rientjes, akpm, linux-mm, linux-kernel,
Linux API
On 8/14/19 5:49 AM, Vlastimil Babka wrote:
> On 8/9/19 8:26 PM, Yang Shi wrote:
>> Here the new counter is introduced for patch 2/2 to account deferred
>> split THPs into available memory since NR_ANON_THPS may contain
>> non-deferred split THPs.
>>
>> I could use an internal counter for deferred split THPs, but if it is
>> accounted by mod_node_page_state, why not just show it in /proc/meminfo?
> The answer to "Why not" is that it becomes part of userspace API (btw this
> patchset should have CC'd linux-api@ - please do for further iterations) and
> even if the implementation detail of deferred splitting might change in the
> future, we'll basically have to keep the counter (even with 0 value) in
> /proc/meminfo forever.
>
> Also, quite recently we have added the following counter:
>
> KReclaimable: Kernel allocations that the kernel will attempt to reclaim
> under memory pressure. Includes SReclaimable (below), and other
> direct allocations with a shrinker.
>
> Although THP allocations are not exactly "kernel allocations", once they are
> unmapped, they are in fact kernel-only, so IMHO it wouldn't be a big stretch to
> add the lazy THP pages there?
Thanks a lot for the suggestion. I agree it may be a good fit. Hope
"kernel allocations" not cause confusion. But, we can explain in the
documentation.
>
>> Or we fix NR_ANON_THPS and show deferred split THPs in /proc/meminfo?
>>
^ permalink raw reply [flat|nested] 3+ messages in thread