From edaae611f6df0d66a8b5a90c84123b72980c7a22 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 22 Feb 2013 17:36:29 +0100 Subject: migration: yay, buffering is gone Buffering was needed because blocking writes could take a long time and starve other threads seeking to grab the big QEMU mutex. Now that all writes (except within _complete callbacks) are done outside the big QEMU mutex, we do not need buffering at all. Reviewed-by: Orit Wasserman Reviewed-by: Juan Quintela Signed-off-by: Paolo Bonzini Signed-off-by: Juan Quintela --- migration.c | 79 ++++++++++++++++--------------------------------------------- 1 file changed, 21 insertions(+), 58 deletions(-) (limited to 'migration.c') diff --git a/migration.c b/migration.c index e64c92d75b..4c8d576701 100644 --- a/migration.c +++ b/migration.c @@ -514,73 +514,41 @@ int64_t migrate_xbzrle_cache_size(void) /* migration thread support */ - -static void buffered_flush(MigrationState *s) -{ - size_t offset = 0; - ssize_t ret = 0; - - DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size); - - if (qemu_file_get_error(s->file)) { - s->buffer_size = 0; - return; - } - qemu_fflush(s->file); - - while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) { - size_t to_send = MIN(s->buffer_size - offset, s->xfer_limit - s->bytes_xfer); - ret = migrate_fd_put_buffer(s, s->buffer + offset, to_send); - if (ret <= 0) { - DPRINTF("error flushing data, %zd\n", ret); - break; - } else { - DPRINTF("flushed %zd byte(s)\n", ret); - offset += ret; - s->bytes_xfer += ret; - } - } - - DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size); - memmove(s->buffer, s->buffer + offset, s->buffer_size - offset); - s->buffer_size -= offset; - - if (ret < 0) { - qemu_file_set_error(s->file, ret); - } -} - static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size) { MigrationState *s = opaque; - ssize_t error; + ssize_t ret; + size_t sent; DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos); - error = qemu_file_get_error(s->file); - if (error) { - DPRINTF("flush when error, bailing: %s\n", strerror(-error)); - return error; + ret = qemu_file_get_error(s->file); + if (ret) { + DPRINTF("flush when error, bailing: %s\n", strerror(-ret)); + return ret; } if (size <= 0) { return size; } - if (size > (s->buffer_capacity - s->buffer_size)) { - DPRINTF("increasing buffer capacity from %zu by %zu\n", - s->buffer_capacity, size + 1024); - - s->buffer_capacity += size + 1024; - - s->buffer = g_realloc(s->buffer, s->buffer_capacity); + sent = 0; + while (size) { + ret = migrate_fd_put_buffer(s, buf, size); + if (ret <= 0) { + DPRINTF("error flushing data, %zd\n", ret); + return ret; + } else { + DPRINTF("flushed %zd byte(s)\n", ret); + sent += ret; + buf += ret; + size -= ret; + s->bytes_xfer += ret; + } } - memcpy(s->buffer + s->buffer_size, buf, size); - s->buffer_size += size; - - return size; + return sent; } static int buffered_close(void *opaque) @@ -712,10 +680,9 @@ static void *buffered_file_thread(void *opaque) g_usleep((initial_time + BUFFER_DELAY - current_time)*1000); sleep_time += qemu_get_clock_ms(rt_clock) - current_time; } - buffered_flush(s); if (qemu_file_get_error(s->file)) { migrate_finish_set_state(s, MIG_STATE_ERROR); - } else if (last_round && s->buffer_size == 0) { + } else if (last_round) { migrate_finish_set_state(s, MIG_STATE_COMPLETED); } } @@ -735,7 +702,6 @@ static void *buffered_file_thread(void *opaque) qemu_bh_schedule(s->cleanup_bh); qemu_mutex_unlock_iothread(); - g_free(s->buffer); return NULL; } @@ -754,9 +720,6 @@ void migrate_fd_connect(MigrationState *s) trace_migrate_set_state(MIG_STATE_ACTIVE); s->bytes_xfer = 0; - s->buffer = NULL; - s->buffer_size = 0; - s->buffer_capacity = 0; /* This is a best 1st approximation. ns to ms */ s->expected_downtime = max_downtime/1000000; -- cgit v1.2.1