From: Peter Xu <peterx@redhat.com>
To: Samuel Zhang <guoqing.zhang@amd.com>
Cc: qemu-devel@nongnu.org, farosas@suse.de, lizhijian@fujitsu.com,
eblake@redhat.com, armbru@redhat.com, Emily.Deng@amd.com,
Victor.Zhao@amd.com, PengJu.Zhou@amd.com, Qing.Ma@amd.com
Subject: Re: [PATCH v5] migration/rdma: add x-rdma-chunk-size parameter
Date: Tue, 14 Apr 2026 18:34:17 -0400 [thread overview]
Message-ID: <ad7A6dUi88Lfohqm@x1.local> (raw)
In-Reply-To: <20260413035703.2602065-1-guoqing.zhang@amd.com>
On Mon, Apr 13, 2026 at 11:57:03AM +0800, Samuel Zhang wrote:
> The default 1MB RDMA chunk size causes slow live migration because
> each chunk triggers a write_flush (ibv_post_send). For 8GB RAM,
> 1MB chunk size produces ~15000 flushes vs ~3700 with 1024MB chunk size.
>
> Add x-rdma-chunk-size parameter to configure the RDMA chunk size for
> faster migration.
> Usage: `migrate_set_parameter x-rdma-chunk-size 1024M`
>
> Performance with RDMA live migration of 8GB RAM VM:
>
> | x-rdma-chunk-size (B) | time (s) | throughput (MB/s) |
> |-----------------------|----------|-------------------|
> | 1M (default) | 37.915 | 1,007 |
> | 32M | 17.880 | 2,260 |
> | 1024M | 4.368 | 17,529 |
>
> Signed-off-by: Samuel Zhang <guoqing.zhang@amd.com>
> Acked-by: Markus Armbruster <armbru@redhat.com>
> Acked-by: Li Zhijian <lizhijian@fujitsu.com>
> Tested-by: Li Zhijian <lizhijian@fujitsu.com>
Acked-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
next prev parent reply other threads:[~2026-04-14 22:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-13 3:57 [PATCH v5] migration/rdma: add x-rdma-chunk-size parameter Samuel Zhang
2026-04-14 16:11 ` Fabiano Rosas
2026-04-14 22:34 ` Peter Xu [this message]
2026-04-24 14:06 ` Peter Xu
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