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Re: [Qemu-devel] [PATCH v6 11/11] migration: create a dedicated thread t
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v6 11/11] migration: create a dedicated thread to release rdma resource |
Date: |
Fri, 17 Aug 2018 15:59:20 +0100 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
* Lidong Chen (address@hidden) 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 <address@hidden>
> ---
> migration/migration.c | 6 ++++++
> migration/migration.h | 3 +++
> migration/rdma.c | 47 +++++++++++++++++++++++++++++++----------------
> 3 files changed, 40 insertions(+), 16 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index f7d6e26..25d9009 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1499,6 +1499,7 @@ void migrate_init(MigrationState *s)
> s->vm_was_running = false;
> s->iteration_initial_bytes = 0;
> s->threshold_size = 0;
> + s->rdma_cleanup_thread_quit = true;
> }
>
> static GSList *migration_blockers;
> @@ -1660,6 +1661,10 @@ static bool migrate_prepare(MigrationState *s, bool
> blk, bool blk_inc,
> return false;
> }
>
> + if (s->rdma_cleanup_thread_quit != true) {
> + return false;
> + }
That's not good! We error out without saying anything to the user
about why; if we error we must always say why, otherwise we'll get
bug reports from people without anyway to debug them.
However, we also don't need to; all we need to do is turn this into
a semaphore or similar, and then wait for it at the start of
'rdma_start_outgoing_migration' - that way there's no error exit, it
just waits a few seconds and then carries on correctly.
(Maybe we need to wait in incoming as well to cope with
postcopy-recovery).
Dave
> if (runstate_check(RUN_STATE_INMIGRATE)) {
> error_setg(errp, "Guest is waiting for an incoming migration");
> return false;
> @@ -3213,6 +3218,7 @@ static void migration_instance_init(Object *obj)
>
> ms->state = MIGRATION_STATUS_NONE;
> ms->mbps = -1;
> + ms->rdma_cleanup_thread_quit = true;
> qemu_sem_init(&ms->pause_sem, 0);
> qemu_mutex_init(&ms->error_mutex);
>
> diff --git a/migration/migration.h b/migration/migration.h
> index 64a7b33..60138dd 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -224,6 +224,9 @@ struct MigrationState
> * do not trigger spurious decompression errors.
> */
> bool decompress_error_check;
> +
> + /* Set this when rdma resource have released */
> + bool rdma_cleanup_thread_quit;
> };
>
> void migrate_set_state(int *state, int old_state, int new_state);
> diff --git a/migration/rdma.c b/migration/rdma.c
> index e1498f2..3282f35 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -2995,35 +2995,50 @@ 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);
> - RDMAContext *rdmain, *rdmaout;
> - trace_qemu_rdma_close();
> -
> - rdmain = rioc->rdmain;
> - if (rdmain) {
> - atomic_rcu_set(&rioc->rdmain, NULL);
> - }
> + RDMAContext **rdma = arg;
> + RDMAContext *rdmain = rdma[0];
> + RDMAContext *rdmaout = rdma[1];
> + MigrationState *s = migrate_get_current();
>
> - rdmaout = rioc->rdmaout;
> - if (rdmaout) {
> - atomic_rcu_set(&rioc->rdmaout, NULL);
> - }
> + rcu_register_thread();
>
> synchronize_rcu();
> -
> if (rdmain) {
> qemu_rdma_cleanup(rdmain);
> }
> -
> if (rdmaout) {
> qemu_rdma_cleanup(rdmaout);
> }
>
> g_free(rdmain);
> g_free(rdmaout);
> + g_free(rdma);
> +
> + rcu_unregister_thread();
> + s->rdma_cleanup_thread_quit = true;
> + return NULL;
> +}
> +
> +static int qio_channel_rdma_close(QIOChannel *ioc,
> + Error **errp)
> +{
> + QemuThread t;
> + QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
> + RDMAContext **rdma = g_new0(RDMAContext*, 2);
> + MigrationState *s = migrate_get_current();
> +
> + trace_qemu_rdma_close();
> + if (rioc->rdmain || rioc->rdmaout) {
> + rdma[0] = rioc->rdmain;
> + rdma[1] = rioc->rdmaout;
> + atomic_rcu_set(&rioc->rdmain, NULL);
> + atomic_rcu_set(&rioc->rdmaout, NULL);
> + s->rdma_cleanup_thread_quit = false;
> + qemu_thread_create(&t, "rdma cleanup", qio_channel_rdma_close_thread,
> + rdma, QEMU_THREAD_DETACHED);
> + }
>
> return 0;
> }
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH v6 01/11] migration: disable RDMA WRITE after postcopy started, (continued)
- [Qemu-devel] [PATCH v6 01/11] migration: disable RDMA WRITE after postcopy started, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 02/11] migration: create a dedicated connection for rdma return path, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 04/11] migration: Stop rdma yielding during incoming postcopy, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 06/11] migration: invoke qio_channel_yield only when qemu_in_coroutine(), Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 03/11] migration: implement bi-directional RDMA QIOChannel, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 07/11] migration: poll the cm event while wait RDMA work request completion, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 05/11] migration: implement io_set_aio_fd_handler function for RDMA QIOChannel, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 08/11] migration: implement the shutdown for RDMA QIOChannel, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 11/11] migration: create a dedicated thread to release rdma resource, Lidong Chen, 2018/08/06
- Re: [Qemu-devel] [PATCH v6 11/11] migration: create a dedicated thread to release rdma resource,
Dr. David Alan Gilbert <=
- [Qemu-devel] [PATCH v6 09/11] migration: poll the cm event for destination qemu, Lidong Chen, 2018/08/06
- [Qemu-devel] [PATCH v6 10/11] migration: remove the unnecessary RDMA_CONTROL_ERROR message, Lidong Chen, 2018/08/06