From: Charan Teja Kalla <charante@codeaurora.org>
To: David Rientjes <rientjes@google.com>
Cc: akpm@linux-foundation.org, vbabka@suse.cz, mhocko@suse.com,
vinmenon@codeaurora.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: page_alloc: update the COMPACT[STALL|FAIL] events properly
Date: Tue, 2 Feb 2021 18:19:46 +0530 [thread overview]
Message-ID: <160ba3b5-2cd4-5ff0-1348-fb477cefd33d@codeaurora.org> (raw)
In-Reply-To: <d9d1dd7b-1fe7-67b6-6ba4-fb1a6faa8fae@google.com>
Thanks David for the review!!
On 2/2/2021 2:54 AM, David Rientjes wrote:
> On Mon, 1 Feb 2021, Charan Teja Reddy wrote:
>
>> By defination, COMPACT[STALL|FAIL] events needs to be counted when there
>
> s/defination/definition/\
Done.
>
>> is 'At least in one zone compaction wasn't deferred or skipped from the
>> direct compaction'. And when compaction is skipped or deferred,
>> COMPACT_SKIPPED will be returned but it will still go and update these
>> compaction events which is wrong in the sense that COMPACT[STALL|FAIL]
>> is counted without even trying the compaction.
>>
>> Correct this by skipping the counting of these events when
>> COMPACT_SKIPPED is returned for compaction. This indirectly also avoid
>> the unnecessary try into the get_page_from_freelist() when compaction is
>> not even tried.
>>
>> Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
>> ---
>> mm/page_alloc.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 519a60d..531f244 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -4152,6 +4152,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
>> memalloc_noreclaim_restore(noreclaim_flag);
>> psi_memstall_leave(&pflags);
>>
>> + if (*compact_result == COMPACT_SKIPPED)
>> + return NULL;
>> /*
>> * At least in one zone compaction wasn't deferred or skipped, so let's
>> * count a compaction stall
>
> This makes sense, I wonder if it would also be useful to check that
> page == NULL, either in try_to_compact_pages() or here for
> COMPACT_SKIPPED?
In the code, when COMPACT_SKIPPED is being returned, the page will
always be NULL. So, I'm not sure how much useful it is for the page ==
NULL check here. Or I failed to understand your point here?
As, till now, COMPACTFAIL also presents page allocation failures because
of the direct compaction is skipped, creating a separate COMPACTSKIPFAIL
event which indicates that 'failed to get the free page as direct
compaction is skipped' is useful?
>
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum, a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2021-02-02 12:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-01 13:48 [PATCH] mm: page_alloc: update the COMPACT[STALL|FAIL] events properly Charan Teja Reddy
2021-02-01 21:24 ` David Rientjes
2021-02-02 12:49 ` Charan Teja Kalla [this message]
2021-02-05 22:28 ` David Rientjes
2021-02-06 1:57 ` Charan Teja Kalla
2021-02-09 16:08 ` Vlastimil Babka
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