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Re: [Qemu-devel] [RFC 13/29] migration: allow src return path to pause
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [RFC 13/29] migration: allow src return path to pause |
Date: |
Tue, 1 Aug 2017 11:01:01 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Peter Xu (address@hidden) wrote:
> Let the thread pause for network issues.
>
> Signed-off-by: Peter Xu <address@hidden>
> ---
> migration/migration.c | 35 +++++++++++++++++++++++++++++++++--
> migration/migration.h | 1 +
> migration/trace-events | 2 ++
> 3 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index c729c5a..d0b9a86 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -996,6 +996,7 @@ static void migrate_fd_cleanup(void *opaque)
> block_cleanup_parameters(s);
>
> qemu_sem_destroy(&s->postcopy_pause_sem);
> + qemu_sem_destroy(&s->postcopy_pause_rp_sem);
> }
>
> void migrate_fd_error(MigrationState *s, const Error *error)
> @@ -1140,6 +1141,7 @@ MigrationState *migrate_init(void)
> error_free(s->error);
> s->error = NULL;
> qemu_sem_init(&s->postcopy_pause_sem, 0);
> + qemu_sem_init(&s->postcopy_pause_rp_sem, 0);
>
> migrate_set_state(&s->state, MIGRATION_STATUS_NONE,
> MIGRATION_STATUS_SETUP);
>
> @@ -1527,6 +1529,18 @@ static void migrate_handle_rp_req_pages(MigrationState
> *ms, const char* rbname,
> }
> }
>
> +/* Return true to retry, false to quit */
> +static bool postcopy_pause_return_path_thread(MigrationState *s)
> +{
> + trace_postcopy_pause_return_path();
> +
> + qemu_sem_wait(&s->postcopy_pause_rp_sem);
> +
> + trace_postcopy_pause_return_path_continued();
> +
> + return true;
> +}
> +
> /*
> * Handles messages sent on the return path towards the source VM
> *
> @@ -1543,6 +1557,8 @@ static void *source_return_path_thread(void *opaque)
> int res;
>
> trace_source_return_path_thread_entry();
> +
> +retry:
> while (!ms->rp_state.error && !qemu_file_get_error(rp) &&
> migration_is_setup_or_active(ms->state)) {
> trace_source_return_path_thread_loop_top();
> @@ -1634,13 +1650,28 @@ static void *source_return_path_thread(void *opaque)
> break;
> }
> }
> - if (qemu_file_get_error(rp)) {
> +
> +out:
> + res = qemu_file_get_error(rp);
> + if (res) {
> + if (res == -EIO) {
> + /*
> + * Maybe there is something we can do: it looks like a
> + * network down issue, and we pause for a recovery.
> + */
> + if (postcopy_pause_return_path_thread(ms)) {
> + /* Reload rp, reset the rest */
> + rp = ms->rp_state.from_dst_file;
> + ms->rp_state.error = false;
> + goto retry;
The recursion trick I suggested in the previous patch might
also work here.
but it's OK, so
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> + }
> + }
> +
> trace_source_return_path_thread_bad_end();
> mark_source_rp_bad(ms);
> }
>
> trace_source_return_path_thread_end();
> -out:
> ms->rp_state.from_dst_file = NULL;
> qemu_fclose(rp);
> return NULL;
> diff --git a/migration/migration.h b/migration/migration.h
> index 08b90e8..7aaab13 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -157,6 +157,7 @@ struct MigrationState
>
> /* Needed by postcopy-pause state */
> QemuSemaphore postcopy_pause_sem;
> + QemuSemaphore postcopy_pause_rp_sem;
> };
>
> void migrate_set_state(int *state, int old_state, int new_state);
> diff --git a/migration/trace-events b/migration/trace-events
> index 22a629e..a269eec 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -98,6 +98,8 @@ migration_thread_setup_complete(void) ""
> open_return_path_on_source(void) ""
> open_return_path_on_source_continue(void) ""
> postcopy_start(void) ""
> +postcopy_pause_return_path(void) ""
> +postcopy_pause_return_path_continued(void) ""
> postcopy_pause_continued(void) ""
> postcopy_pause_incoming(void) ""
> postcopy_pause_incoming_continued(void) ""
> --
> 2.7.4
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
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