linux-kernel - Re: [linus:master] [mm] c0bff412e6: stress-ng.clone.ops_per

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Message-ID: <69f480d6-2dd8-4efb-9516-70d74eceedd5@redhat.com>
Date: Wed, 14 Aug 2024 14:02:44 +0200
From: David Hildenbrand <david@...hat.com>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: Yin Fengwei <fengwei.yin@...el.com>,
 kernel test robot <oliver.sang@...el.com>, Peter Xu <peterx@...hat.com>,
 oe-lkp@...ts.linux.dev, lkp@...el.com, linux-kernel@...r.kernel.org,
 Andrew Morton <akpm@...ux-foundation.org>,
 Huacai Chen <chenhuacai@...nel.org>, Jason Gunthorpe <jgg@...dia.com>,
 Matthew Wilcox <willy@...radead.org>, Nathan Chancellor <nathan@...nel.org>,
 Ryan Roberts <ryan.roberts@....com>, WANG Xuerui <kernel@...0n.name>,
 linux-mm@...ck.org, ying.huang@...el.com, feng.tang@...el.com
Subject: Re: [linus:master] [mm] c0bff412e6: stress-ng.clone.ops_per_sec -2.9%
 regression

On 14.08.24 13:06, Mateusz Guzik wrote:
> On Wed, Aug 14, 2024 at 11:45 AM David Hildenbrand <david@...hat.com> wrote:
>>
>> On 14.08.24 06:10, Mateusz Guzik wrote:
>>> On Wed, Aug 14, 2024 at 5:02 AM Yin Fengwei <fengwei.yin@...el.com> wrote:
>>>>
>>>> On 8/13/24 03:14, Mateusz Guzik wrote:
>>>>> would you mind benchmarking the change which merely force-inlines _compund_page?
>>>>>
>>>>> https://lore.kernel.org/linux-mm/66c4fcc5-47f6-438c-a73a-3af6e19c3200@redhat.com/
>>>> This change can resolve the regression also:
>>>
>>> Great, thanks.
>>>
>>> David, I guess this means it would be fine to inline the entire thing
>>> at least from this bench standpoint. Given that this is your idea I
>>> guess you should do the needful(tm)? :)
>>
>> Testing
>>
>> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
>> index 5769fe6e4950..25e25b34f4a0 100644
>> --- a/include/linux/page-flags.h
>> +++ b/include/linux/page-flags.h
>> @@ -235,7 +235,7 @@ static __always_inline int page_is_fake_head(const struct page *page)
>>           return page_fixed_fake_head(page) != page;
>>    }
>>
>> -static inline unsigned long _compound_head(const struct page *page)
>> +static __always_inline unsigned long _compound_head(const struct page *page)
>>    {
>>           unsigned long head = READ_ONCE(page->compound_head);
>>
>>
>> With a kernel-config based on something derived from Fedora
>> config-6.8.9-100.fc38.x86_64 for convenience with
>>
>> CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP=y
>>
>> add/remove: 15/14 grow/shrink: 79/87 up/down: 12836/-13917 (-1081)
> [snip]
>> Total: Before=32786363, After=32785282, chg -0.00%
> 
> I guess there should be no opposition then?
> 
> Given that this is your patch I presume you are going to see this through.

I was hoping that you could send an official patch, after all you did 
most of the work here.

> 
> I don't want any mention or cc on the patch, thanks for understanding :)

If I have to send it I will respect it.

-- 
Cheers,

David / dhildenb