From: Christoph Hellwig <hch@lst.de>
To: Chao Leng <lengchao@huawei.com>
Cc: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me,
kbusch@kernel.org
Subject: Re: [PATCH] nvme-rdma: set ack timeout of RoCE to 262ms
Date: Sun, 21 Aug 2022 08:20:16 +0200 [thread overview]
Message-ID: <20220821062016.GA26553@lst.de> (raw)
In-Reply-To: <20220819075825.21231-1-lengchao@huawei.com>
On Fri, Aug 19, 2022 at 03:58:25PM +0800, Chao Leng wrote:
> Now the ack timeout of RoCE is 2 second(2^(18+1)*4us=2 second). In the
> case of low concurrency, if some packets lost due to network abnormal
> such as network rerouting, Optical fiber signal interference, etc,
> it will wait 2 second to try retransmitting the lost packets.
> As a result, the I/O latency is greater than 2 seconds.
> The I/O latency is so long for real-time transaction service. Indeed we
> do not have to wait so long time to make sure that packets are lost.
> Setting the ack timeout to 262ms(2^(15+1)*4us=262ms) is sufficient.
I'll leave people more familar with RoCE to judge the merits of this
change, but I really want a comment explaining the choice in the
source code.
next prev parent reply other threads:[~2022-08-21 6:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 7:58 [PATCH] nvme-rdma: set ack timeout of RoCE to 262ms Chao Leng
2022-08-21 6:20 ` Christoph Hellwig [this message]
2022-08-22 9:50 ` Chao Leng
2022-08-22 15:30 ` Max Gurtovoy
2022-08-25 9:58 ` Chao Leng
2022-08-28 14:57 ` Sagi Grimberg
2022-08-29 8:05 ` Chao Leng
2022-08-29 9:06 ` Sagi Grimberg
2022-08-29 13:15 ` Chao Leng
2022-10-10 9:12 ` Chao Leng
2022-10-14 0:05 ` Max Gurtovoy
2022-10-14 2:15 ` Chao Leng
2022-11-16 2:24 ` Chao Leng
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