From: Song Liu <song@kernel.org>
To: tada keisuke <keisuke1.tada@kioxia.com>
Cc: "yukuai3@huawei.com" <yukuai3@huawei.com>,
"linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/11] md: avoid counter operation conflicts
Date: Wed, 10 Apr 2024 14:13:50 -0700 [thread overview]
Message-ID: <CAPhsuW6iDjPp2B-NEqMEjb9v40US9eN88CuOc+882h6+BRCAQw@mail.gmail.com> (raw)
In-Reply-To: <a022f547c43e40e2b9f0aebb2bd0bfa8@kioxia.com>
Thanks for the patchset!
On Tue, Mar 26, 2024 at 3:29 AM tada keisuke <keisuke1.tada@kioxia.com> wrote:
>
> Currently, active_aligned_reads and nr_pending used as counters are atomic types.
> Therefore, when inc/dec in a multi-core results in conflicts.
>
> To solve this problem, use "percpu_ref" counters that can avoid conflicts and maintain consistency.
>
> Switch modes of percpu_ref to achieve both consistency and conflict avoidance.
> During normal operations such as inc/dec, it operates as percpu mode.
> When consistency is required, it operates as atomic mode.
> The operations that require consistency are as follows:
> ・Zero check for the counter
> ・All operations in RAID 1/10
IIUC, the patchset is to resolve race conditions and thus improve performance.
If this is the case, could you please include some performance numbers in the
next version?
Thanks,
Song
prev parent reply other threads:[~2024-04-10 21:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-26 10:29 [PATCH 00/11] md: avoid counter operation conflicts tada keisuke
2024-03-26 14:01 ` Yu Kuai
2024-03-27 1:27 ` tada keisuke
2024-04-10 21:13 ` Song Liu [this message]
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