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Subject: Re: [PATCH -next 0/3] md/raid10: reduce lock contention for io
To:     Yu Kuai <yukuai1@huaweicloud.com>, song@kernel.org
Cc:     linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        yukuai3@huawei.com, yi.zhang@huawei.com
References: <20220829131502.165356-1-yukuai1@huaweicloud.com>
From:   Guoqing Jiang <guoqing.jiang@linux.dev>
Message-ID: <691f9d94-f650-0f04-2d49-74fe84c24bfe@linux.dev>
Date:   Mon, 29 Aug 2022 21:40:51 +0800
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On 8/29/22 9:14 PM, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
>
> patch 1 is a small problem found by code review.
> patch 2 avoid holding resync_lock in fast path.
> patch 3 avoid holding lock in wake_up() in fast path.
>
> Test environment:
>
> Architecture: aarch64
> Cpu: Huawei KUNPENG 920, there are four numa nodes
>
> Raid10 initialize:
> mdadm --create /dev/md0 --level 10 --bitmap none --raid-devices 4 /dev/nvme0n1 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme3n1
>
> Test cmd:
> fio -name=0 -ioengine=libaio -direct=1 -group_reporting=1 -randseed=2022 -rwmixread=70 -refill_buffers -filename=/dev/md0 -numjobs=16 -runtime=60s -bs=4k -iodepth=256 -rw=randread
>
> Test result:
> before this patchset:	2.9 GiB/s
> after this patchset:	6.6 Gib/s

Impressive! Pls try mdadm test suites too to avoid regression.

> Please noted that in kunpeng-920, memory access latency is very bad
> accross nodes compare to local node, and in other architecture
> performance improvement might not be significant.

By any chance can someone try with x64?

Thanks,
Guoqing