* Lidong Chen (jemmy858...@gmail.com) wrote:
> ibv_dereg_mr wait for a long time for big memory size virtual server.
>
> The test result is:
> 10GB 326ms
> 20GB 699ms
> 30GB 1021ms
> 40GB 1387ms
> 50GB 1712ms
> 60GB 2034ms
> 70GB 2457ms
> 80GB 2807ms
> 90GB 3107ms
> 100GB 3474ms
> 110GB 3735ms
> 120GB 4064ms
> 130GB 4567ms
> 140GB 4886ms
>
> this will cause the guest os hang for a while when migration finished.
> So create a dedicated thread to release rdma resource.
>
> Signed-off-by: Lidong Chen <lidongc...@tencent.com>
> ---
> migration/rdma.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/migration/rdma.c b/migration/rdma.c
> index dfa4f77..1b9e261 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -2979,12 +2979,12 @@ static void
> qio_channel_rdma_set_aio_fd_handler(QIOChannel *ioc,
> }
> }
>
> -static int qio_channel_rdma_close(QIOChannel *ioc,
> - Error **errp)
> +static void *qio_channel_rdma_close_thread(void *arg)
> {
> - QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
> + QIOChannelRDMA *rioc = arg;
> RDMAContext *rdmain, *rdmaout;
> - trace_qemu_rdma_close();
> +
> + rcu_register_thread();
>
> rdmain = rioc->rdmain;
> if (rdmain) {
> @@ -3009,6 +3009,19 @@ static int qio_channel_rdma_close(QIOChannel *ioc,
> g_free(rdmain);
> g_free(rdmaout);
>
> + rcu_unregister_thread();
> + return NULL;
> +}
> +
> +static int qio_channel_rdma_close(QIOChannel *ioc,
> + Error **errp)
> +{
> + QemuThread t;
> + QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
> + trace_qemu_rdma_close();
> +
> + qemu_thread_create(&t, "rdma cleanup", qio_channel_rdma_close_thread,
> + rioc, QEMU_THREAD_DETACHED);
I don't think this can be this simple; consider the lock in patch 4;
now that lock means qui_channel_rdma_close() can't be called in
parallel; but with this change it means:
f->lock
qemu_thread_create (1)
!f->lock
f->lock
qemu_thread_create
!f->lock
so we don't really protect the thing you were trying to lock
Dave
> return 0;
> }
>
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
