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From: David Hildenbrand <david@redhat.com>
To: Lance Yang <ioworker0@gmail.com>, akpm@linux-foundation.org
Cc: mhocko@suse.com, zokeefe@google.com, songmuchun@bytedance.com,
	shy828301@gmail.com, peterx@redhat.com, minchan@kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] mm/khugepaged: bypassing unnecessary scans with MMF_DISABLE_THP check
Date: Thu, 22 Feb 2024 09:51:00 +0100	[thread overview]
Message-ID: <84fc211a-075d-44c7-a4c3-698931b6dc7c@redhat.com> (raw)
In-Reply-To: <CAK1f24nk19eciysFqvTd=rqpiKePhstDWEEQ_mvT89WCDNrWNQ@mail.gmail.com>

On 22.02.24 08:51, Lance Yang wrote:
> Hey,
> 
> On an Intel Core i5 CPU, the time taken by
> khugepaged to scan the address space of
> the process, which has been set with the
> MMF_DISABLE_THP flag after being added
> to the mm_slots list, is as follows (shorter is better):
> 
> VMA Count |   Old   |   New   |  Change
> ---------------------------------------
>      50     |   23us  |    9us  |  -60.9%
>     100     |   32us  |    9us  |  -71.9%
>     200     |   44us  |    9us  |  -79.5%
>     400     |   75us  |    9us  |  -88.0%
>     800     |   98us  |    9us  |  -90.8%
> 
> IIUC, once the count of VMAs for the process
> exceeds page_to_scan, khugepaged needs to
> wait for scan_sleep_millisecs ms before scanning
> the next process. IMO, unnecessary scans could
> actually be skipped with a very inexpensive
> mm->flags check in this case.

FWIW

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb


  reply	other threads:[~2024-02-22  8:51 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-29  5:45 [PATCH 1/1] mm/khugepaged: bypassing unnecessary scans with MMF_DISABLE_THP check Lance Yang
2024-01-29 16:28 ` Michal Hocko
2024-01-30  2:12   ` Lance Yang
2024-01-30  3:08     ` Lance Yang
2024-01-30  9:35       ` Michal Hocko
2024-01-30  9:46         ` Lance Yang
2024-01-31  0:37           ` Lance Yang
2024-01-29 18:53 ` Yang Shi
2024-01-29 19:03   ` Zach O'Keefe
2024-01-30  2:37     ` Lance Yang
2024-01-30  2:21   ` Lance Yang
2024-01-31  9:30 ` Lance Yang
2024-01-31 20:06   ` Yang Shi
2024-02-01  1:13     ` Lance Yang
2024-02-01 18:56       ` Yang Shi
2024-02-03  3:20         ` Lance Yang
2024-02-21 22:11   ` Andrew Morton
2024-02-22  7:43     ` Lance Yang
2024-02-22  7:51   ` Lance Yang
2024-02-22  8:51     ` David Hildenbrand [this message]
2024-02-22  9:12       ` Lance Yang
2024-02-22 20:23     ` Yang Shi
2024-02-22 21:11       ` Andrew Morton
2024-02-23  7:59         ` Lance Yang
2024-02-24  1:47         ` Yang Shi
2024-02-24  1:46 ` Yang Shi
2024-02-24  3:54   ` Lance Yang
2024-02-25  4:56     ` Lance Yang

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