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>

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,

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;

blockdev.c

@@ -441,6 +441,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
     const char *buf;
     int bdrv_flags = 0;
     int on_read_error, on_write_error;
+    bool account_invalid, account_failed;
     BlockBackend *blk;
     BlockDriverState *bs;
     ThrottleConfig cfg;
@@ -477,6 +478,9 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
     /* extract parameters */
     snapshot = qemu_opt_get_bool(opts, "snapshot", 0);
 
+    account_invalid = qemu_opt_get_bool(opts, "stats-account-invalid", true);
+    account_failed = qemu_opt_get_bool(opts, "stats-account-failed", true);
+
     extract_common_blockdev_options(opts, &bdrv_flags, &throttling_group, &cfg,
                                     &detect_zeroes, &error);
     if (error) {
@@ -573,6 +577,8 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
         if (bdrv_key_required(bs)) {
             autostart = 0;
         }
+
+        block_acct_init(blk_get_stats(blk), account_invalid, account_failed);
     }
 
     blk_set_on_error(blk, on_read_error, on_write_error);
@@ -3900,6 +3906,16 @@ QemuOptsList qemu_common_drive_opts = {
             .name = "detect-zeroes",
             .type = QEMU_OPT_STRING,
             .help = "try to optimize zero writes (off, on, unmap)",
+        },{
+            .name = "stats-account-invalid",
+            .type = QEMU_OPT_BOOL,
+            .help = "whether to account for invalid I/O operations "
+                    "in the statistics",
+        },{
+            .name = "stats-account-failed",
+            .type = QEMU_OPT_BOOL,
+            .help = "whether to account for failed I/O operations "
+                    "in the statistics",
         },
         { /* end of list */ }
     },

include/block/accounting.h

@@ -25,6 +25,7 @@
 #define BLOCK_ACCOUNTING_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
 #include "qemu/typedefs.h"
 
@@ -43,6 +44,8 @@ typedef struct BlockAcctStats {
     uint64_t total_time_ns[BLOCK_MAX_IOTYPE];
     uint64_t merged[BLOCK_MAX_IOTYPE];
     int64_t last_access_time_ns;
+    bool account_invalid;
+    bool account_failed;
 } BlockAcctStats;
 
 typedef struct BlockAcctCookie {
@@ -51,6 +54,8 @@ typedef struct BlockAcctCookie {
     enum BlockAcctType type;
 } BlockAcctCookie;
 
+void block_acct_init(BlockAcctStats *stats, bool account_invalid,
+                     bool account_failed);
 void block_acct_start(BlockAcctStats *stats, BlockAcctCookie *cookie,
                       int64_t bytes, enum BlockAcctType type);
 void block_acct_done(BlockAcctStats *stats, BlockAcctCookie *cookie);

qapi/block-core.json

@@ -470,6 +470,12 @@
 # @invalid_flush_operations: The number of invalid flush operations
 #                            performed by the device (Since 2.5)
 #
+# @account_invalid: Whether invalid operations are included in the
+#                   last access statistics (Since 2.5)
+#
+# @account_failed: Whether failed operations are included in the
+#                  latency and last access statistics (Since 2.5)
+#
 # Since: 0.14.0
 ##
 { 'struct': 'BlockDeviceStats',
@@ -480,7 +486,8 @@
            'rd_merged': 'int', 'wr_merged': 'int', '*idle_time_ns': 'int',
            'failed_rd_operations': 'int', 'failed_wr_operations': 'int',
            'failed_flush_operations': 'int', 'invalid_rd_operations': 'int',
-           'invalid_wr_operations': 'int', 'invalid_flush_operations': 'int'  } }
+           'invalid_wr_operations': 'int', 'invalid_flush_operations': 'int',
+           'account_invalid': 'bool', 'account_failed': 'bool' } }
 
 ##
 # @BlockStats:
@@ -1461,6 +1468,12 @@
 #                 (default: enospc)
 # @read-only:     #optional whether the block device should be read-only
 #                 (default: false)
+# @stats-account-invalid: #optional whether to include invalid
+#                         operations when computing last access statistics
+#                         (default: true) (Since 2.5)
+# @stats-account-failed: #optional whether to include failed
+#                         operations when computing latency and last
+#                         access statistics (default: true) (Since 2.5)
 # @detect-zeroes: #optional detect and optimize zero writes (Since 2.1)
 #                 (default: off)
 #
@@ -1476,6 +1489,8 @@
             '*rerror': 'BlockdevOnError',
             '*werror': 'BlockdevOnError',
             '*read-only': 'bool',
+            '*stats-account-invalid': 'bool',
+            '*stats-account-failed': 'bool',
             '*detect-zeroes': 'BlockdevDetectZeroesOptions' } }
 
 ##

qmp-commands.hx

@@ -2599,6 +2599,11 @@ Each json-object contain the following:
                                (json-int)
     - "invalid_flush_operations": number of invalid flush operations
                                   (json-int)
+    - "account_invalid": whether invalid operations are included in
+                         the last access statistics (json-bool)
+    - "account_failed": whether failed operations are included in the
+                         latency and last access statistics
+                         (json-bool)
 - "parent": Contains recursively the statistics of the underlying
             protocol (e.g. the host file for a qcow2 image). If there is
             no underlying protocol, this field is omitted
@@ -2624,7 +2629,9 @@ Example:
                   "flush_operations":61,
                   "rd_merged":0,
                   "wr_merged":0,
-                  "idle_time_ns":2953431879
+                  "idle_time_ns":2953431879,
+                  "account_invalid":true,
+                  "account_failed":false
                }
             },
             "stats":{
@@ -2639,7 +2646,9 @@ Example:
                "flush_total_times_ns":49653,
                "rd_merged":0,
                "wr_merged":0,
-               "idle_time_ns":2953431879
+               "idle_time_ns":2953431879,
+               "account_invalid":true,
+               "account_failed":false
             }
          },
          {
@@ -2655,7 +2664,9 @@ Example:
                "rd_total_times_ns":0
                "flush_total_times_ns":0,
                "rd_merged":0,
-               "wr_merged":0
+               "wr_merged":0,
+               "account_invalid":false,
+               "account_failed":false
             }
          },
          {
@@ -2671,7 +2682,9 @@ Example:
                "rd_total_times_ns":0
                "flush_total_times_ns":0,
                "rd_merged":0,
-               "wr_merged":0
+               "wr_merged":0,
+               "account_invalid":false,
+               "account_failed":false
             }
          },
          {
@@ -2687,7 +2700,9 @@ Example:
                "rd_total_times_ns":0
                "flush_total_times_ns":0,
                "rd_merged":0,
-               "wr_merged":0
+               "wr_merged":0,
+               "account_invalid":false,
+               "account_failed":false
             }
          }
       ]