Re: [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check

From	Vlastimil Babka <vbabka@suse.cz>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check
Date	2016-04-27 15:00 +0200
Message-ID	<rsxes-1nA-47@gated-at.bofh.it> (permalink)
References	<rswim-Gj-11@gated-at.bofh.it> <rsws2-11E-17@gated-at.bofh.it> <rswV3-1g9-1@gated-at.bofh.it>
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On 04/27/2016 02:37 PM, Mel Gorman wrote:
> On Wed, Apr 27, 2016 at 02:01:14PM +0200, Vlastimil Babka wrote:
>> !DEBUG_VM bloat-o-meter:
>>
>> add/remove: 1/0 grow/shrink: 0/2 up/down: 124/-383 (-259)
>> function                                     old     new   delta
>> free_pages_check_bad                           -     124    +124
>> free_pcppages_bulk                          1509    1403    -106
>> __free_pages_ok                             1025     748    -277
>>
>> DEBUG_VM:
>>
>> add/remove: 1/0 grow/shrink: 0/1 up/down: 124/-242 (-118)
>> function                                     old     new   delta
>> free_pages_check_bad                           -     124    +124
>> free_pages_prepare                          1048     806    -242
>>
>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>
> This uninlines the check all right but it also introduces new function
> calls into the free path. As it's the free fast path, I suspect it would
> be a step in the wrong direction from a performance perspective.

Oh expected this to be a non-issue as the call only happens when a bad 
page is actually encountered, which is rare? But if you can measure some 
overhead here then sure.

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Re: [PATCH 27/28] mm, page_alloc: Defer debugging checks of freed  pages until a PCP drain Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:00 +0200
  [PATCH 2/3] mm, page_alloc: pull out side effects from free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:10 +0200
    Re: [PATCH 2/3] mm, page_alloc: pull out side effects from  free_pages_check Mel Gorman <mgorman@techsingularity.net> - 2016-04-27 14:50 +0200
      Re: [PATCH 2/3] mm, page_alloc: pull out side effects from  free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 15:10 +0200
  [PATCH 3/3] mm, page_alloc: don't duplicate code in free_pcp_prepare Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:10 +0200
  [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 14:10 +0200
    Re: [PATCH 1/3] mm, page_alloc: un-inline the bad part of  free_pages_check Mel Gorman <mgorman@techsingularity.net> - 2016-04-27 14:40 +0200
      Re: [PATCH 1/3] mm, page_alloc: un-inline the bad part of  free_pages_check Vlastimil Babka <vbabka@suse.cz> - 2016-04-27 15:00 +0200

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