block: Allow configuring whether to account failed and invalid ops

This patch adds two options, "stats-account-invalid" and
"stats-account-failed", that can be used to decide whether invalid and
failed I/O operations must be used when collecting statistics for
latency and last access time.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: ebc7e5966511a342cad428a392c5f5ad56b15213.1446044837.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 22 insertions, 5 deletions

diff --git a/block/accounting.c b/block/accounting.c
index 49a9444..923aeaf 100644
--- a/block/accounting.c
+++ b/block/accounting.c
@@ -28,6 +28,13 @@
 
 static QEMUClockType clock_type = QEMU_CLOCK_REALTIME;
 
+void block_acct_init(BlockAcctStats *stats, bool account_invalid,
+                     bool account_failed)
+{
+    stats->account_invalid = account_invalid;
+    stats->account_failed = account_failed;
+}
+
 void block_acct_start(BlockAcctStats *stats, BlockAcctCookie *cookie,
                       int64_t bytes, enum BlockAcctType type)
 {
@@ -53,13 +60,17 @@ void block_acct_done(BlockAcctStats *stats, BlockAcctCookie *cookie)
 
 void block_acct_failed(BlockAcctStats *stats, BlockAcctCookie *cookie)
 {
-    int64_t time_ns = qemu_clock_get_ns(clock_type);
-
     assert(cookie->type < BLOCK_MAX_IOTYPE);
 
     stats->failed_ops[cookie->type]++;
-    stats->total_time_ns[cookie->type] += time_ns - cookie->start_time_ns;
-    stats->last_access_time_ns = time_ns;
+
+    if (stats->account_failed) {
+        int64_t time_ns = qemu_clock_get_ns(clock_type);
+        int64_t latency_ns = time_ns - cookie->start_time_ns;
+
+        stats->total_time_ns[cookie->type] += latency_ns;
+        stats->last_access_time_ns = time_ns;
+    }
 }
 
 void block_acct_invalid(BlockAcctStats *stats, enum BlockAcctType type)
@@ -72,7 +83,10 @@ void block_acct_invalid(BlockAcctStats *stats, enum BlockAcctType type)
      * therefore there's no actual I/O involved. */
 
     stats->invalid_ops[type]++;
-    stats->last_access_time_ns = qemu_clock_get_ns(clock_type);
+
+    if (stats->account_invalid) {
+        stats->last_access_time_ns = qemu_clock_get_ns(clock_type);
+    }
 }
 
 void block_acct_merge_done(BlockAcctStats *stats, enum BlockAcctType type,
diff --git a/block/qapi.c b/block/qapi.c
index d1a6bdc..083469a 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -372,6 +372,9 @@ static BlockStats *bdrv_query_stats(const BlockDriverState *bs,
         if (s->stats->has_idle_time_ns) {
             s->stats->idle_time_ns = block_acct_idle_time_ns(stats);
         }
+
+        s->stats->account_invalid = stats->account_invalid;
+        s->stats->account_failed = stats->account_failed;
     }
 
     s->stats->wr_highest_offset = bs->wr_highest_offset;