From: Matthew Wilcox <willy@infradead.org>
To: lizhe.67@bytedance.com
Cc: akpm@linux-foundation.org, boqun.feng@gmail.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
longman@redhat.com, mingo@redhat.com, peterz@infradead.org,
will@kernel.org
Subject: Re: [RFC 2/2] khugepaged: use upgrade_read() to optimize collapse_huge_page
Date: Thu, 17 Oct 2024 14:20:12 +0100 [thread overview]
Message-ID: <ZxEPDMUnYlAy3r3_@casper.infradead.org> (raw)
In-Reply-To: <20241017061841.81240-1-lizhe.67@bytedance.com>
On Thu, Oct 17, 2024 at 02:18:41PM +0800, lizhe.67@bytedance.com wrote:
> On Wed, 16 Oct 2024 12:53:15 +0100, willy@infradead.org wrote:
>
> >On Wed, Oct 16, 2024 at 12:36:00PM +0800, lizhe.67@bytedance.com wrote:
> >> From: Li Zhe <lizhe.67@bytedance.com>
> >>
> >> In function collapse_huge_page(), we drop mmap read lock and get
> >> mmap write lock to prevent most accesses to pagetables. There is
> >> a small time window to allow other tasks to acquire the mmap lock.
> >> With the use of upgrade_read(), we don't need to check vma and pmd
> >> again in most cases.
> >
> >This is clearly a performance optimisation. So you must have some
> >numebrs that justify this, please include them.
>
> Yes, I will add the relevant data to v2 patch.
How about telling us all now so we know whether to continue discussing
this?
next prev parent reply other threads:[~2024-10-17 13:20 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-16 4:35 [RFC 0/2] rwsem: introduce upgrade_read interface lizhe.67
2024-10-16 4:35 ` [RFC 1/2] " lizhe.67
2024-10-16 4:56 ` Christoph Hellwig
2024-10-16 7:33 ` lizhe.67
2024-10-16 7:36 ` Christoph Hellwig
2024-10-16 8:00 ` lizhe.67
2024-10-16 8:03 ` Christoph Hellwig
2024-10-16 8:13 ` lizhe.67
2024-10-16 11:51 ` Matthew Wilcox
2024-10-16 12:21 ` Christoph Hellwig
2024-10-16 11:49 ` Matthew Wilcox
2024-10-17 6:23 ` lizhe.67
2024-10-16 14:23 ` Waiman Long
2024-10-16 18:05 ` Matthew Wilcox
2024-10-16 18:39 ` Waiman Long
2024-10-17 6:46 ` lizhe.67
2024-10-17 15:05 ` Christoph Hellwig
2024-10-17 17:36 ` Waiman Long
2024-10-18 5:06 ` Christoph Hellwig
2024-10-19 22:59 ` kernel test robot
2024-10-16 4:36 ` [RFC 2/2] khugepaged: use upgrade_read() to optimize collapse_huge_page lizhe.67
2024-10-16 11:53 ` Matthew Wilcox
2024-10-17 6:18 ` lizhe.67
2024-10-17 13:20 ` Matthew Wilcox [this message]
2024-10-18 6:37 ` lizhe.67
2024-10-23 7:27 ` kernel test robot
2024-10-16 8:09 ` [RFC 0/2] rwsem: introduce upgrade_read interface Peter Zijlstra
2024-10-16 8:53 ` lizhe.67
2024-10-16 12:10 ` Peter Zijlstra
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