qapi: add block latency histogram interface
Set (and clear) histograms through new command
block-latency-histogram-set and show new statistics in
query-blockstats results.
For now, the command is marked experimental with prefix 'x-',
to gain experience with the interface without being stuck
with design decisions.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20180309165212.97144-3-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[eblake: fix typos, mention x- prefix in commit message]
Signed-off-by: Eric Blake <eblake@redhat.com>
diff --git a/blockdev.c b/blockdev.c
index 5048e73..c31bf3d 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -4239,6 +4239,49 @@
aio_context_release(old_context);
}
+void qmp_x_block_latency_histogram_set(
+ const char *device,
+ bool has_boundaries, uint64List *boundaries,
+ bool has_boundaries_read, uint64List *boundaries_read,
+ bool has_boundaries_write, uint64List *boundaries_write,
+ bool has_boundaries_flush, uint64List *boundaries_flush,
+ Error **errp)
+{
+ BlockBackend *blk = blk_by_name(device);
+ BlockAcctStats *stats;
+
+ if (!blk) {
+ error_setg(errp, "Device '%s' not found", device);
+ return;
+ }
+ stats = blk_get_stats(blk);
+
+ if (!has_boundaries && !has_boundaries_read && !has_boundaries_write &&
+ !has_boundaries_flush)
+ {
+ block_latency_histograms_clear(stats);
+ return;
+ }
+
+ if (has_boundaries || has_boundaries_read) {
+ block_latency_histogram_set(
+ stats, BLOCK_ACCT_READ,
+ has_boundaries_read ? boundaries_read : boundaries);
+ }
+
+ if (has_boundaries || has_boundaries_write) {
+ block_latency_histogram_set(
+ stats, BLOCK_ACCT_WRITE,
+ has_boundaries_write ? boundaries_write : boundaries);
+ }
+
+ if (has_boundaries || has_boundaries_flush) {
+ block_latency_histogram_set(
+ stats, BLOCK_ACCT_FLUSH,
+ has_boundaries_flush ? boundaries_flush : boundaries);
+ }
+}
+
QemuOptsList qemu_common_drive_opts = {
.name = "drive",
.head = QTAILQ_HEAD_INITIALIZER(qemu_common_drive_opts.head),
