linux-kernel - Re: [PATCH v2 1/2] mm:vmscan: the dirty folio in folio

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Date:   Tue, 24 Oct 2023 10:04:26 +0800
From:   zhiguojiang <justinjiang@...o.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, opensource.kernel@...o.com
Subject: Re: [PATCH v2 1/2] mm:vmscan: the dirty folio in folio_list skip
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在 2023/10/23 21:01, Matthew Wilcox 写道:
> On Mon, Oct 23, 2023 at 08:44:55PM +0800, zhiguojiang wrote:
>> 在 2023/10/23 20:21, Matthew Wilcox 写道:
>>> On Mon, Oct 23, 2023 at 04:07:28PM +0800, zhiguojiang wrote:
>>>>> Are you seeing measurable changes for any workloads?  It certainly seems
>>>>> like you should, but it would help if you chose a test from mmtests and
>>>>> showed how performance changed on your system.
>>>> In one mmtest, the max times for a invalid recyling of a folio_list dirty
>>>> folio that does not support pageout and has been activated in
>>>> shrink_folio_list() are: cost=51us, exe=2365us.
>>>>
>>>> Calculate according to this formula: dirty_cost / total_cost * 100%, the
>>>> recyling efficiency of dirty folios can be improved 53.13%、82.95%.
>>>>
>>>> So this patch can optimize shrink efficiency and reduce the workload of
>>>> kswapd to a certain extent.
>>>>
>>>> kswapd0-96      (     96) [005] .....   387.218548:
>>>> mm_vmscan_lru_shrink_inactive: [Justin] nid 0 nr_scanned 32 nr_taken 32
>>>> nr_reclaimed 31 nr_dirty  1 nr_unqueued_dirty  1 nr_writeback 0
>>>> nr_activate[1]  1 nr_ref_keep  0 f RECLAIM_WB_FILE|RECLAIM_WB_ASYNC
>>>> total_cost 96 total_exe 2365 dirty_cost 51 total_exe 2365
>>>>
>>>> kswapd0-96      (     96) [006] .....   412.822532:
>>>> mm_vmscan_lru_shrink_inactive: [Justin] nid 0 nr_scanned 32 nr_taken 32
>>>> nr_reclaimed  0 nr_dirty 32 nr_unqueued_dirty 32 nr_writeback 0
>>>> nr_activate[1] 19 nr_ref_keep 13 f RECLAIM_WB_FILE|RECLAIM_WB_ASYNC
>>>> total_cost 88 total_exe 605  dirty_cost 73 total_exe 605
>>> I appreciate that you can put probes in and determine the cost, but do
>>> you see improvements for a real workload?  Like doing a kernel compile
>>> -- does it speed up at all?
>> Can you help share a method for testing thread workload, like kswapd?
> Something dirt simple like 'time make -j8'.
Two compilations were conducted separately, and compared to the 
unmodified compilation,
the compilation time for adding modified patches had a certain 
reduction, as follows:

Compilation command:
make distclean -j8
make ARCH=x86_64 x86_64_defconfig
time make -j8

1.Unmodified Compilation time:
real    2m40.276s
user    16m2.956s
sys     2m14.738s

real    2m40.136s
user    16m2.617s
sys     2m14.722s

2.[Patch v2 1/2] Modified Compilation time:
real    2m40.067s
user    16m3.164s
sys     2m14.211s

real    2m40.123s
user    16m2.439s
sys     2m14.508s

3 [Patch v2 1/2] + [Patch v2 2/2] Modified Compilation time:
real    2m40.367s
user    16m3.738s
sys     2m13.662s

real    2m40.014s
user    16m3.108s
sys     2m14.096s