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Re: [PATCH 1/2] migration: Fix rdma migration failed
From: |
Zhijian Li (Fujitsu) |
Subject: |
Re: [PATCH 1/2] migration: Fix rdma migration failed |
Date: |
Thu, 21 Sep 2023 01:40:33 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 |
Sorry to all, i forgot to update my email address to lizhijian@fujitsu.com.
Corrected it.
On 20/09/2023 17:04, 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) {