From: Peter Xu <peterx@redhat.com>
To: Li Zhijian <lizhijian@fujitsu.com>
Cc: quintela@redhat.com, leobras@redhat.com, qemu-devel@nongnu.org,
Li Zhijian <lizhijian@cn.fujitsu.com>
Subject: Re: [PATCH 1/2] migration: Fix rdma migration failed
Date: Fri, 22 Sep 2023 11:42:08 -0400 [thread overview]
Message-ID: <ZQ210LoAWDIJ5l9J@x1n> (raw)
In-Reply-To: <20230920090412.726725-1-lizhijian@fujitsu.com>
On Wed, Sep 20, 2023 at 05:04:11PM +0800, Li Zhijian wrote:
> From: Li Zhijian <lizhijian@cn.fujitsu.com>
>
> Destination will fail with:
> qemu-system-x86_64: rdma: Too many requests in this message (3638950032).Bailing.
>
> migrate with RDMA is different from tcp. RDMA has its own control
> message, and all traffic between RDMA_CONTROL_REGISTER_REQUEST and
> RDMA_CONTROL_REGISTER_FINISHED should not be disturbed.
>
> find_dirty_block() will be called during RDMA_CONTROL_REGISTER_REQUEST
> and RDMA_CONTROL_REGISTER_FINISHED, it will send a extra traffic to
> destination and cause migration to fail.
>
> Since there's no existing subroutine to indicate whether it's migrated
> by RDMA or not, and RDMA is not compatible with multifd, we use
> migrate_multifd() here.
>
> Fixes: 294e5a4034 ("multifd: Only flush once each full round of memory")
> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> ---
> migration/ram.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 9040d66e61..89ae28e21a 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1399,7 +1399,8 @@ static int find_dirty_block(RAMState *rs, PageSearchStatus *pss)
> pss->page = 0;
> pss->block = QLIST_NEXT_RCU(pss->block, next);
> if (!pss->block) {
> - if (!migrate_multifd_flush_after_each_section()) {
> + if (migrate_multifd() &&
> + !migrate_multifd_flush_after_each_section()) {
> QEMUFile *f = rs->pss[RAM_CHANNEL_PRECOPY].pss_channel;
> int ret = multifd_send_sync_main(f);
> if (ret < 0) {
> --
> 2.31.1
>
Maybe better to put that check at the entry of
migrate_multifd_flush_after_each_section()?
I also hope that some day there's no multifd function called in generic
migration code paths..
--
Peter Xu
next prev parent reply other threads:[~2023-09-22 15:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 9:04 [PATCH 1/2] migration: Fix rdma migration failed Li Zhijian
2023-09-20 9:04 ` [PATCH 2/2] migration/rdma: zore out head.repeat to make the error more clear Li Zhijian
2023-09-20 13:01 ` Fabiano Rosas
2023-09-21 1:36 ` Zhijian Li (Fujitsu)
2023-09-21 12:29 ` Fabiano Rosas
2023-09-22 15:44 ` Peter Xu
2023-09-20 12:46 ` [PATCH 1/2] migration: Fix rdma migration failed Fabiano Rosas
2023-09-22 7:42 ` Zhijian Li (Fujitsu)
2023-09-21 1:40 ` Zhijian Li (Fujitsu)
2023-09-22 15:42 ` Peter Xu [this message]
2023-09-22 15:59 ` Fabiano Rosas
2023-09-22 16:09 ` Peter Xu
2023-09-25 8:59 ` Zhijian Li (Fujitsu)
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