[Qemu-devel] [PATCH v2 0/3] Add block size histogram qapi interface

[Qemu-devel] [PATCH v2 0/3] Add block size histogram qapi interface

[zhenwei pi]

Modify command 'block-latency-histogram-set' to make block histogram
interface common to use. And support block size histogram.
Thanks to Eric Blake&Vladimir Sementsov-Ogievskiy for the suggestions.

This command has been tested for half year on QEMU-2.12, and we found
that 3K+ virtual machines write 25GB/s totally, the block size
histogram like following:
        0 ~ 8k: 58% ~ 62%
        8k ~ 32k: 10% ~ 12%
        32k ~ 128k: 2% ~ 3%
        128K ~ 512K: 24% ~ 26%
        512K ~ : ...

And the histogram data help us to optimise backend distributed
storage.

Changelog:
v2:
  - make 'block-latency-histogram-set' common.
  - remove duplicated functions.
  - fix uncommon indentation(reviewed by Vladimir Sementsov-Ogievskiy).

zhenwei pi (3):
  block/accounting: rename struct BlockLatencyHistogram
  block/accounting: introduce block size histogram
  qapi: make block histogram interface common

 block/accounting.c         |  62 ++++++++++++++++++++--------
 block/qapi.c               |  32 ++++++++------
 blockdev.c                 |  33 +++++++++++----
 include/block/accounting.h |  13 +++---
 qapi/block-core.json       | 101 +++++++++++++++++++++++++++------------------
 5 files changed, 158 insertions(+), 83 deletions(-)

-- 
2.11.0

[Qemu-devel] [PATCH v2 1/3] block/accounting: rename struct BlockLatencyHistogram

[zhenwei pi]

Rename struct BlockLatencyHistogram to BlockHistogram, and rename
related functions.
Make this struct and functions be common, they can be used widely.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/accounting.c         | 44 +++++++++++++++++++++++++++-----------------
 block/qapi.c               | 23 +++++++++++------------
 include/block/accounting.h |  8 ++++----
 3 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/block/accounting.c b/block/accounting.c
index 70a3d9a426..d210a73fe9 100644
--- a/block/accounting.c
+++ b/block/accounting.c
@@ -94,13 +94,14 @@ void block_acct_start(BlockAcctStats *stats, BlockAcctCookie *cookie,
     cookie->type = type;
 }
 
-/* block_latency_histogram_compare_func:
+/**
+ * block_histogram_compare_func:
  * Compare @key with interval [@it[0], @it[1]).
  * Return: -1 if @key < @it[0]
  *          0 if @key in [@it[0], @it[1])
  *         +1 if @key >= @it[1]
  */
-static int block_latency_histogram_compare_func(const void *key, const void *it)
+static int block_histogram_compare_func(const void *key, const void *it)
 {
     uint64_t k = *(uint64_t *)key;
     uint64_t a = ((uint64_t *)it)[0];
@@ -109,8 +110,7 @@ static int block_latency_histogram_compare_func(const void *key, const void *it)
     return k < a ? -1 : (k < b ? 0 : 1);
 }
 
-static void block_latency_histogram_account(BlockLatencyHistogram *hist,
-                                            int64_t latency_ns)
+static void block_histogram_account(BlockHistogram *hist, int64_t val)
 {
     uint64_t *pos;
 
@@ -120,28 +120,26 @@ static void block_latency_histogram_account(BlockLatencyHistogram *hist,
     }
 
 
-    if (latency_ns < hist->boundaries[0]) {
+    if (val < hist->boundaries[0]) {
         hist->bins[0]++;
         return;
     }
 
-    if (latency_ns >= hist->boundaries[hist->nbins - 2]) {
+    if (val >= hist->boundaries[hist->nbins - 2]) {
         hist->bins[hist->nbins - 1]++;
         return;
     }
 
-    pos = bsearch(&latency_ns, hist->boundaries, hist->nbins - 2,
+    pos = bsearch(&val, hist->boundaries, hist->nbins - 2,
                   sizeof(hist->boundaries[0]),
-                  block_latency_histogram_compare_func);
+                  block_histogram_compare_func);
     assert(pos != NULL);
 
     hist->bins[pos - hist->boundaries + 1]++;
 }
 
-int block_latency_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
-                                uint64List *boundaries)
+static int block_histogram_set(BlockHistogram *hist, uint64List *boundaries)
 {
-    BlockLatencyHistogram *hist = &stats->latency_histogram[type];
     uint64List *entry;
     uint64_t *ptr;
     uint64_t prev = 0;
@@ -170,15 +168,27 @@ int block_latency_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
     return 0;
 }
 
+static void block_histogram_clear(BlockHistogram *hist)
+{
+    g_free(hist->bins);
+    g_free(hist->boundaries);
+    memset(hist, 0, sizeof(*hist));
+}
+
+int block_latency_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
+                                uint64List *boundaries)
+{
+    BlockHistogram *hist = &stats->latency_histogram[type];
+
+    return block_histogram_set(hist, boundaries);
+}
+
 void block_latency_histograms_clear(BlockAcctStats *stats)
 {
     int i;
 
     for (i = 0; i < BLOCK_MAX_IOTYPE; i++) {
-        BlockLatencyHistogram *hist = &stats->latency_histogram[i];
-        g_free(hist->bins);
-        g_free(hist->boundaries);
-        memset(hist, 0, sizeof(*hist));
+        block_histogram_clear(&stats->latency_histogram[i]);
     }
 }
 
@@ -204,8 +214,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
         stats->nr_ops[cookie->type]++;
     }
 
-    block_latency_histogram_account(&stats->latency_histogram[cookie->type],
-                                    latency_ns);
+    block_histogram_account(&stats->latency_histogram[cookie->type],
+                            latency_ns);
 
     if (!failed || stats->account_failed) {
         stats->total_time_ns[cookie->type] += latency_ns;
diff --git a/block/qapi.c b/block/qapi.c
index 917435f022..9d9b2f1927 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -415,9 +415,8 @@ static uint64List *uint64_list(uint64_t *list, int size)
     return out_list;
 }
 
-static void bdrv_latency_histogram_stats(BlockLatencyHistogram *hist,
-                                         bool *not_null,
-                                         BlockLatencyHistogramInfo **info)
+static void bdrv_histogram_stats(BlockHistogram *hist, bool *not_null,
+                                 BlockLatencyHistogramInfo **info)
 {
     *not_null = hist->bins != NULL;
     if (*not_null) {
@@ -494,15 +493,15 @@ static void bdrv_query_blk_stats(BlockDeviceStats *ds, BlockBackend *blk)
             block_acct_queue_depth(ts, BLOCK_ACCT_WRITE);
     }
 
-    bdrv_latency_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_READ],
-                                 &ds->has_rd_latency_histogram,
-                                 &ds->rd_latency_histogram);
-    bdrv_latency_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_WRITE],
-                                 &ds->has_wr_latency_histogram,
-                                 &ds->wr_latency_histogram);
-    bdrv_latency_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_FLUSH],
-                                 &ds->has_flush_latency_histogram,
-                                 &ds->flush_latency_histogram);
+    bdrv_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_READ],
+                         &ds->has_rd_latency_histogram,
+                         &ds->rd_latency_histogram);
+    bdrv_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_WRITE],
+                         &ds->has_wr_latency_histogram,
+                         &ds->wr_latency_histogram);
+    bdrv_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_FLUSH],
+                         &ds->has_flush_latency_histogram,
+                         &ds->flush_latency_histogram);
 }
 
 static BlockStats *bdrv_query_bds_stats(BlockDriverState *bs,
diff --git a/include/block/accounting.h b/include/block/accounting.h
index d1f67b10dd..270fddb69c 100644
--- a/include/block/accounting.h
+++ b/include/block/accounting.h
@@ -46,7 +46,7 @@ struct BlockAcctTimedStats {
     QSLIST_ENTRY(BlockAcctTimedStats) entries;
 };
 
-typedef struct BlockLatencyHistogram {
+typedef struct BlockHistogram {
     /* The following histogram is represented like this:
      *
      * 5|           *
@@ -57,7 +57,7 @@ typedef struct BlockLatencyHistogram {
      *  +------------------
      *      10   50   100
      *
-     * BlockLatencyHistogram histogram = {
+     * BlockHistogram histogram = {
      *     .nbins = 4,
      *     .boundaries = {10, 50, 100},
      *     .bins = {3, 1, 5, 2},
@@ -74,7 +74,7 @@ typedef struct BlockLatencyHistogram {
     uint64_t *boundaries; /* @nbins-1 numbers here
                              (all boundaries, except 0 and +inf) */
     uint64_t *bins;
-} BlockLatencyHistogram;
+} BlockHistogram;
 
 struct BlockAcctStats {
     QemuMutex lock;
@@ -88,7 +88,7 @@ struct BlockAcctStats {
     QSLIST_HEAD(, BlockAcctTimedStats) intervals;
     bool account_invalid;
     bool account_failed;
-    BlockLatencyHistogram latency_histogram[BLOCK_MAX_IOTYPE];
+    BlockHistogram latency_histogram[BLOCK_MAX_IOTYPE];
 };
 
 typedef struct BlockAcctCookie {
-- 
2.11.0

[Qemu-devel] [PATCH v2 2/3] block/accounting: introduce block size histogram

[zhenwei pi]

Introduce block size histogram statics for block devices.

For read/write/flush operation type, the block size region
[0, +inf) is divided into subregions by several points.
It works like block latency histogram.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/accounting.c         | 18 ++++++++++++++++++
 include/block/accounting.h |  5 ++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/block/accounting.c b/block/accounting.c
index d210a73fe9..3a1e41a971 100644
--- a/block/accounting.c
+++ b/block/accounting.c
@@ -192,6 +192,22 @@ void block_latency_histograms_clear(BlockAcctStats *stats)
     }
 }
 
+int block_size_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
+                             uint64List *boundaries)
+{
+    BlockHistogram *hist = &stats->size_histogram[type];
+
+    return block_histogram_set(hist, boundaries);
+}
+
+void block_size_histograms_clear(BlockAcctStats *stats)
+{
+    int i;
+
+    for (i = 0; i < BLOCK_MAX_IOTYPE; i++) {
+        block_histogram_clear(&stats->size_histogram[i]);
+    }
+}
 static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
                                  bool failed)
 {
@@ -216,6 +232,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
 
     block_histogram_account(&stats->latency_histogram[cookie->type],
                             latency_ns);
+    block_histogram_account(&stats->size_histogram[cookie->type],
+                            cookie->bytes);
 
     if (!failed || stats->account_failed) {
         stats->total_time_ns[cookie->type] += latency_ns;
diff --git a/include/block/accounting.h b/include/block/accounting.h
index 270fddb69c..0fbba64408 100644
--- a/include/block/accounting.h
+++ b/include/block/accounting.h
@@ -89,6 +89,7 @@ struct BlockAcctStats {
     bool account_invalid;
     bool account_failed;
     BlockHistogram latency_histogram[BLOCK_MAX_IOTYPE];
+    BlockHistogram size_histogram[BLOCK_MAX_IOTYPE];
 };
 
 typedef struct BlockAcctCookie {
@@ -117,5 +118,7 @@ double block_acct_queue_depth(BlockAcctTimedStats *stats,
 int block_latency_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
                                 uint64List *boundaries);
 void block_latency_histograms_clear(BlockAcctStats *stats);
-
+int block_size_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
+                             uint64List *boundaries);
+void block_size_histograms_clear(BlockAcctStats *stats);
 #endif
-- 
2.11.0

[Qemu-devel] [PATCH v2 3/3] qapi: make block histogram interface common

[zhenwei pi]

Modify command 'block-latency-histogram-set' to 'block-histogram-set'
and modify struct 'BlockLatencyHistogramInfo' to struct
'BlockHistogramInfo', this makes block histogram interface common to
use.

Currently 'BlockHistogramType' supports 'latency', it works as same
as the old command 'block-latency-histogram-set'. New enum 'size'
allows QEMU to fill histogram by block I/O size in byte.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block/qapi.c         |  11 +++++-
 blockdev.c           |  33 +++++++++++++----
 qapi/block-core.json | 101 +++++++++++++++++++++++++++++++--------------------
 3 files changed, 95 insertions(+), 50 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c
index 9d9b2f1927..c778b2c376 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -416,11 +416,11 @@ static uint64List *uint64_list(uint64_t *list, int size)
 }
 
 static void bdrv_histogram_stats(BlockHistogram *hist, bool *not_null,
-                                 BlockLatencyHistogramInfo **info)
+                                 BlockHistogramInfo **info)
 {
     *not_null = hist->bins != NULL;
     if (*not_null) {
-        *info = g_new0(BlockLatencyHistogramInfo, 1);
+        *info = g_new0(BlockHistogramInfo, 1);
 
         (*info)->boundaries = uint64_list(hist->boundaries, hist->nbins - 1);
         (*info)->bins = uint64_list(hist->bins, hist->nbins);
@@ -502,6 +502,13 @@ static void bdrv_query_blk_stats(BlockDeviceStats *ds, BlockBackend *blk)
     bdrv_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_FLUSH],
                          &ds->has_flush_latency_histogram,
                          &ds->flush_latency_histogram);
+    bdrv_histogram_stats(&stats->size_histogram[BLOCK_ACCT_READ],
+                         &ds->has_rd_size_histogram, &ds->rd_size_histogram);
+    bdrv_histogram_stats(&stats->size_histogram[BLOCK_ACCT_WRITE],
+                         &ds->has_wr_size_histogram, &ds->wr_size_histogram);
+    bdrv_histogram_stats(&stats->size_histogram[BLOCK_ACCT_FLUSH],
+                         &ds->has_flush_size_histogram,
+                         &ds->flush_size_histogram);
 }
 
 static BlockStats *bdrv_query_bds_stats(BlockDriverState *bs,
diff --git a/blockdev.c b/blockdev.c
index 5d6a13dea9..82240ae8c5 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -4507,8 +4507,9 @@ void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
     aio_context_release(old_context);
 }
 
-void qmp_block_latency_histogram_set(
+void qmp_block_histogram_set(
     const char *id,
+    BlockHistogramType type,
     bool has_boundaries, uint64List *boundaries,
     bool has_boundaries_read, uint64List *boundaries_read,
     bool has_boundaries_write, uint64List *boundaries_write,
@@ -4517,24 +4518,42 @@ void qmp_block_latency_histogram_set(
 {
     BlockBackend *blk = qmp_get_blk(NULL, id, errp);
     BlockAcctStats *stats;
+    void (*clear_func)(BlockAcctStats *stats);
+    int (*set_func)(BlockAcctStats *stats, enum BlockAcctType type,
+                    uint64List *boundaries);
     int ret;
 
     if (!blk) {
         return;
     }
 
+    switch (type) {
+    case BLOCK_HISTOGRAM_TYPE_LATENCY: {
+        clear_func = block_latency_histograms_clear;
+        set_func = block_latency_histogram_set;
+        break;
+    }
+    case BLOCK_HISTOGRAM_TYPE_SIZE: {
+        clear_func = block_size_histograms_clear;
+        set_func = block_size_histogram_set;
+        break;
+    }
+    default:
+        error_setg(errp, "Unsupported block histogram type");
+        return;
+    }
+
     stats = blk_get_stats(blk);
 
     if (!has_boundaries && !has_boundaries_read && !has_boundaries_write &&
         !has_boundaries_flush)
     {
-        block_latency_histograms_clear(stats);
+        clear_func(stats);
         return;
     }
 
     if (has_boundaries || has_boundaries_read) {
-        ret = block_latency_histogram_set(
-            stats, BLOCK_ACCT_READ,
+        ret = set_func(stats, BLOCK_ACCT_READ,
             has_boundaries_read ? boundaries_read : boundaries);
         if (ret) {
             error_setg(errp, "Device '%s' set read boundaries fail", id);
@@ -4543,8 +4562,7 @@ void qmp_block_latency_histogram_set(
     }
 
     if (has_boundaries || has_boundaries_write) {
-        ret = block_latency_histogram_set(
-            stats, BLOCK_ACCT_WRITE,
+        ret = set_func(stats, BLOCK_ACCT_WRITE,
             has_boundaries_write ? boundaries_write : boundaries);
         if (ret) {
             error_setg(errp, "Device '%s' set write boundaries fail", id);
@@ -4553,8 +4571,7 @@ void qmp_block_latency_histogram_set(
     }
 
     if (has_boundaries || has_boundaries_flush) {
-        ret = block_latency_histogram_set(
-            stats, BLOCK_ACCT_FLUSH,
+        ret = set_func(stats, BLOCK_ACCT_FLUSH,
             has_boundaries_flush ? boundaries_flush : boundaries);
         if (ret) {
             error_setg(errp, "Device '%s' set flush boundaries fail", id);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 0d43d4f37c..b3b8d714d3 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -533,12 +533,12 @@
            'flags': ['Qcow2BitmapInfoFlags'] } }
 
 ##
-# @BlockLatencyHistogramInfo:
+# @BlockHistogramInfo:
 #
-# Block latency histogram.
+# Block histogram.
 #
-# @boundaries: list of interval boundary values in nanoseconds, all greater
-#              than zero and in ascending order.
+# @boundaries: list of interval boundary values, all greater than zero and in
+#              ascending order.
 #              For example, the list [10, 50, 100] produces the following
 #              histogram intervals: [0, 10), [10, 50), [50, 100), [100, +inf).
 #
@@ -555,57 +555,72 @@
 #         +------------------
 #             10   50   100
 #
-# Since: 4.0
+# Since: 4.1
 ##
-{ 'struct': 'BlockLatencyHistogramInfo',
+{ 'struct': 'BlockHistogramInfo',
   'data': {'boundaries': ['uint64'], 'bins': ['uint64'] } }
 
 ##
-# @block-latency-histogram-set:
+# @BlockHistogramType:
 #
-# Manage read, write and flush latency histograms for the device.
+# An enumeration of block histogram type.
 #
-# If only @id parameter is specified, remove all present latency histograms
-# for the device. Otherwise, add/reset some of (or all) latency histograms.
+# @latency: The histogram is filled by block I/O latency in nanosecond.
+#
+# @size: The histogram is filled by block I/O size in byte.
+#
+# Since: 4.1
+##
+{ 'enum': 'BlockHistogramType', 'data': [ 'latency', 'size' ] }
+
+##
+# @block-histogram-set:
+#
+# Manage read, write and flush @BlockHistogramType histograms for the device.
+#
+# If only @id and @type parameter are specified, remove all present @type
+# histograms for the device. Otherwise, add/reset some of (or all) @type
+# histograms.
 #
 # @id: The name or QOM path of the guest device.
 #
+# @type: The type @BlockHistogramType of histogram.
+#
 # @boundaries: list of interval boundary values (see description in
-#              BlockLatencyHistogramInfo definition). If specified, all
-#              latency histograms are removed, and empty ones created for all
-#              io types with intervals corresponding to @boundaries (except for
-#              io types, for which specific boundaries are set through the
-#              following parameters).
+#              BlockHistogramInfo definition). If specified, all histograms
+#              are removed, and empty ones created for all io types with
+#              intervals corresponding to @boundaries (except for io types
+#              for which specific boundaries are set through the following
+#              parameters).
 #
-# @boundaries-read: list of interval boundary values for read latency
-#                   histogram. If specified, old read latency histogram is
-#                   removed, and empty one created with intervals
-#                   corresponding to @boundaries-read. The parameter has higher
-#                   priority then @boundaries.
+# @boundaries-read: list of interval boundary values for read histogram. If
+#                   specified, old read histogram is removed, and empty one
+#                   created with intervals corresponding to @boundaries-read.
+#                   The parameter has higher priority then @boundaries.
 #
-# @boundaries-write: list of interval boundary values for write latency
-#                    histogram.
+# @boundaries-write: list of interval boundary values for write histogram.
 #
-# @boundaries-flush: list of interval boundary values for flush latency
-#                    histogram.
+# @boundaries-flush: list of interval boundary values for flush histogram.
 #
 # Returns: error if device is not found or any boundary arrays are invalid.
 #
-# Since: 4.0
+# Since: 4.1
 #
-# Example: set new histograms for all io types with intervals
+# Example: set new latency histograms for all io types with intervals
 # [0, 10), [10, 50), [50, 100), [100, +inf):
 #
-# -> { "execute": "block-latency-histogram-set",
+# -> { "execute": "block-histogram-set",
 #      "arguments": { "id": "drive0",
+#                     "type":"latency",
 #                     "boundaries": [10, 50, 100] } }
 # <- { "return": {} }
 #
-# Example: set new histogram only for write, other histograms will remain
-# not changed (or not created):
+# Example: set new latency histogram only for write, other histograms will
+# remain not changed (or not created):
 #
-# -> { "execute": "block-latency-histogram-set",
+# -> { "execute": "block-histogram-set",
 #      "arguments": { "id": "drive0",
+#                     "type":"latency",
 #                     "boundaries-write": [10, 50, 100] } }
 # <- { "return": {} }
 #
@@ -613,20 +628,23 @@
 #   read, flush: [0, 10), [10, 50), [50, 100), [100, +inf)
 #   write: [0, 1000), [1000, 5000), [5000, +inf)
 #
-# -> { "execute": "block-latency-histogram-set",
+# -> { "execute": "block-histogram-set",
 #      "arguments": { "id": "drive0",
+#                     "type":"latency",
 #                     "boundaries": [10, 50, 100],
 #                     "boundaries-write": [1000, 5000] } }
 # <- { "return": {} }
 #
 # Example: remove all latency histograms:
 #
-# -> { "execute": "block-latency-histogram-set",
-#      "arguments": { "id": "drive0" } }
+# -> { "execute": "block-histogram-set",
+#      "arguments": { "id": "drive0"
+#                     "type":"latency"} }
 # <- { "return": {} }
 ##
-{ 'command': 'block-latency-histogram-set',
+{ 'command': 'block-histogram-set',
   'data': {'id': 'str',
+           'type': 'BlockHistogramType',
            '*boundaries': ['uint64'],
            '*boundaries-read': ['uint64'],
            '*boundaries-write': ['uint64'],
@@ -912,11 +930,11 @@
 # @timed_stats: Statistics specific to the set of previously defined
 #               intervals of time (Since 2.5)
 #
-# @rd_latency_histogram: @BlockLatencyHistogramInfo. (Since 4.0)
+# @rd_latency_histogram: @BlockHistogramInfo. (Since 4.1)
 #
-# @wr_latency_histogram: @BlockLatencyHistogramInfo. (Since 4.0)
+# @wr_latency_histogram: @BlockHistogramInfo. (Since 4.1)
 #
-# @flush_latency_histogram: @BlockLatencyHistogramInfo. (Since 4.0)
+# @flush_latency_histogram: @BlockHistogramInfo. (Since 4.1)
 #
 # Since: 0.14.0
 ##
@@ -931,9 +949,12 @@
            'invalid_wr_operations': 'int', 'invalid_flush_operations': 'int',
            'account_invalid': 'bool', 'account_failed': 'bool',
            'timed_stats': ['BlockDeviceTimedStats'],
-           '*rd_latency_histogram': 'BlockLatencyHistogramInfo',
-           '*wr_latency_histogram': 'BlockLatencyHistogramInfo',
-           '*flush_latency_histogram': 'BlockLatencyHistogramInfo' } }
+           '*rd_latency_histogram': 'BlockHistogramInfo',
+           '*wr_latency_histogram': 'BlockHistogramInfo',
+           '*flush_latency_histogram': 'BlockHistogramInfo',
+           '*rd_size_histogram': 'BlockHistogramInfo',
+           '*wr_size_histogram': 'BlockHistogramInfo',
+           '*flush_size_histogram': 'BlockHistogramInfo' } }
 
 ##
 # @BlockStats:
-- 
2.11.0

Re: [Qemu-devel] [PATCH v2 3/3] qapi: make block histogram interface common

[Vladimir Sementsov-Ogievskiy]

08.07.2019 12:32, zhenwei pi wrote:
> Modify command 'block-latency-histogram-set' to 'block-histogram-set'
> and modify struct 'BlockLatencyHistogramInfo' to struct
> 'BlockHistogramInfo', this makes block histogram interface common to
> use.
> 
> Currently 'BlockHistogramType' supports 'latency', it works as same
> as the old command 'block-latency-histogram-set'. New enum 'size'
> allows QEMU to fill histogram by block I/O size in byte.
> 
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>


Hi Zhenwei!

You should add "Reviewed-by" marks only after someone give them,
writing it in reply to your patch. If someones reply don't have
such mark, you should not add it.

> ---
>   block/qapi.c         |  11 +++++-
>   blockdev.c           |  33 +++++++++++++----
>   qapi/block-core.json | 101 +++++++++++++++++++++++++++++++--------------------
>   3 files changed, 95 insertions(+), 50 deletions(-)
> 
> diff --git a/block/qapi.c b/block/qapi.c
> index 9d9b2f1927..c778b2c376 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -416,11 +416,11 @@ static uint64List *uint64_list(uint64_t *list, int size)
>   }
>   
>   static void bdrv_histogram_stats(BlockHistogram *hist, bool *not_null,
> -                                 BlockLatencyHistogramInfo **info)
> +                                 BlockHistogramInfo **info)
>   {
>       *not_null = hist->bins != NULL;
>       if (*not_null) {
> -        *info = g_new0(BlockLatencyHistogramInfo, 1);
> +        *info = g_new0(BlockHistogramInfo, 1);
>   
>           (*info)->boundaries = uint64_list(hist->boundaries, hist->nbins - 1);
>           (*info)->bins = uint64_list(hist->bins, hist->nbins);
> @@ -502,6 +502,13 @@ static void bdrv_query_blk_stats(BlockDeviceStats *ds, BlockBackend *blk)
>       bdrv_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_FLUSH],
>                            &ds->has_flush_latency_histogram,
>                            &ds->flush_latency_histogram);
> +    bdrv_histogram_stats(&stats->size_histogram[BLOCK_ACCT_READ],
> +                         &ds->has_rd_size_histogram, &ds->rd_size_histogram);
> +    bdrv_histogram_stats(&stats->size_histogram[BLOCK_ACCT_WRITE],
> +                         &ds->has_wr_size_histogram, &ds->wr_size_histogram);
> +    bdrv_histogram_stats(&stats->size_histogram[BLOCK_ACCT_FLUSH],
> +                         &ds->has_flush_size_histogram,
> +                         &ds->flush_size_histogram);
>   }
>   
>   static BlockStats *bdrv_query_bds_stats(BlockDriverState *bs,
> diff --git a/blockdev.c b/blockdev.c
> index 5d6a13dea9..82240ae8c5 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -4507,8 +4507,9 @@ void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
>       aio_context_release(old_context);
>   }
>   
> -void qmp_block_latency_histogram_set(
> +void qmp_block_histogram_set(
>       const char *id,
> +    BlockHistogramType type,
>       bool has_boundaries, uint64List *boundaries,
>       bool has_boundaries_read, uint64List *boundaries_read,
>       bool has_boundaries_write, uint64List *boundaries_write,
> @@ -4517,24 +4518,42 @@ void qmp_block_latency_histogram_set(
>   {
>       BlockBackend *blk = qmp_get_blk(NULL, id, errp);
>       BlockAcctStats *stats;
> +    void (*clear_func)(BlockAcctStats *stats);
> +    int (*set_func)(BlockAcctStats *stats, enum BlockAcctType type,
> +                    uint64List *boundaries);
>       int ret;
>   
>       if (!blk) {
>           return;
>       }
>   
> +    switch (type) {
> +    case BLOCK_HISTOGRAM_TYPE_LATENCY: {
> +        clear_func = block_latency_histograms_clear;
> +        set_func = block_latency_histogram_set;

Hmm, seems too tricky. This is because we have mapping (int type) -> (stats field name).

And these two functions are mostly duplication, the difference is that they works with different
fields.

So, I think better to combine both size_histogram and latency_histogram to one array field, where
index is histogram type. This will reduce duplication and we can drop this switch(){}.

> +        break;
> +    }
> +    case BLOCK_HISTOGRAM_TYPE_SIZE: {
> +        clear_func = block_size_histograms_clear;
> +        set_func = block_size_histogram_set;
> +        break;
> +    }
> +    default:
> +        error_setg(errp, "Unsupported block histogram type");
> +        return;
> +    }
> +
>       stats = blk_get_stats(blk);
>   
>       if (!has_boundaries && !has_boundaries_read && !has_boundaries_write &&
>           !has_boundaries_flush)
>       {
> -        block_latency_histograms_clear(stats);
> +        clear_func(stats);
>           return;
>       }
>   
>       if (has_boundaries || has_boundaries_read) {
> -        ret = block_latency_histogram_set(
> -            stats, BLOCK_ACCT_READ,
> +        ret = set_func(stats, BLOCK_ACCT_READ,
>               has_boundaries_read ? boundaries_read : boundaries);
>           if (ret) {
>               error_setg(errp, "Device '%s' set read boundaries fail", id);
> @@ -4543,8 +4562,7 @@ void qmp_block_latency_histogram_set(
>       }
>   
>       if (has_boundaries || has_boundaries_write) {
> -        ret = block_latency_histogram_set(
> -            stats, BLOCK_ACCT_WRITE,
> +        ret = set_func(stats, BLOCK_ACCT_WRITE,
>               has_boundaries_write ? boundaries_write : boundaries);
>           if (ret) {
>               error_setg(errp, "Device '%s' set write boundaries fail", id);
> @@ -4553,8 +4571,7 @@ void qmp_block_latency_histogram_set(
>       }
>   
>       if (has_boundaries || has_boundaries_flush) {
> -        ret = block_latency_histogram_set(
> -            stats, BLOCK_ACCT_FLUSH,
> +        ret = set_func(stats, BLOCK_ACCT_FLUSH,
>               has_boundaries_flush ? boundaries_flush : boundaries);
>           if (ret) {
>               error_setg(errp, "Device '%s' set flush boundaries fail", id);
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 0d43d4f37c..b3b8d714d3 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json

And about qapi part:

1. Eric, as I understand we should not drop old command but deprecate it and add a new one?
2. 4.1 -> 4.2

> @@ -533,12 +533,12 @@
>              'flags': ['Qcow2BitmapInfoFlags'] } }
>   
>   ##
> -# @BlockLatencyHistogramInfo:
> +# @BlockHistogramInfo:
>   #
> -# Block latency histogram.
> +# Block histogram.
>   #
> -# @boundaries: list of interval boundary values in nanoseconds, all greater
> -#              than zero and in ascending order.
> +# @boundaries: list of interval boundary values, all greater than zero and in
> +#              ascending order.
>   #              For example, the list [10, 50, 100] produces the following
>   #              histogram intervals: [0, 10), [10, 50), [50, 100), [100, +inf).
>   #
> @@ -555,57 +555,72 @@
>   #         +------------------
>   #             10   50   100
>   #
> -# Since: 4.0
> +# Since: 4.1
>   ##
> -{ 'struct': 'BlockLatencyHistogramInfo',
> +{ 'struct': 'BlockHistogramInfo',
>     'data': {'boundaries': ['uint64'], 'bins': ['uint64'] } }
>   
>   ##
> -# @block-latency-histogram-set:
> +# @BlockHistogramType:
>   #
> -# Manage read, write and flush latency histograms for the device.
> +# An enumeration of block histogram type.
>   #
> -# If only @id parameter is specified, remove all present latency histograms
> -# for the device. Otherwise, add/reset some of (or all) latency histograms.
> +# @latency: The histogram is filled by block I/O latency in nanosecond.
> +#
> +# @size: The histogram is filled by block I/O size in byte.
> +#
> +# Since: 4.1
> +##
> +{ 'enum': 'BlockHistogramType', 'data': [ 'latency', 'size' ] }
> +
> +##
> +# @block-histogram-set:
> +#
> +# Manage read, write and flush @BlockHistogramType histograms for the device.
> +#
> +# If only @id and @type parameter are specified, remove all present @type
> +# histograms for the device. Otherwise, add/reset some of (or all) @type
> +# histograms.
>   #
>   # @id: The name or QOM path of the guest device.
>   #
> +# @type: The type @BlockHistogramType of histogram.
> +#
>   # @boundaries: list of interval boundary values (see description in
> -#              BlockLatencyHistogramInfo definition). If specified, all
> -#              latency histograms are removed, and empty ones created for all
> -#              io types with intervals corresponding to @boundaries (except for
> -#              io types, for which specific boundaries are set through the
> -#              following parameters).
> +#              BlockHistogramInfo definition). If specified, all histograms
> +#              are removed, and empty ones created for all io types with
> +#              intervals corresponding to @boundaries (except for io types
> +#              for which specific boundaries are set through the following
> +#              parameters).
>   #
> -# @boundaries-read: list of interval boundary values for read latency
> -#                   histogram. If specified, old read latency histogram is
> -#                   removed, and empty one created with intervals
> -#                   corresponding to @boundaries-read. The parameter has higher
> -#                   priority then @boundaries.
> +# @boundaries-read: list of interval boundary values for read histogram. If
> +#                   specified, old read histogram is removed, and empty one
> +#                   created with intervals corresponding to @boundaries-read.
> +#                   The parameter has higher priority then @boundaries.
>   #
> -# @boundaries-write: list of interval boundary values for write latency
> -#                    histogram.
> +# @boundaries-write: list of interval boundary values for write histogram.
>   #
> -# @boundaries-flush: list of interval boundary values for flush latency
> -#                    histogram.
> +# @boundaries-flush: list of interval boundary values for flush histogram.
>   #
>   # Returns: error if device is not found or any boundary arrays are invalid.
>   #
> -# Since: 4.0
> +# Since: 4.1
>   #
> -# Example: set new histograms for all io types with intervals
> +# Example: set new latency histograms for all io types with intervals
>   # [0, 10), [10, 50), [50, 100), [100, +inf):
>   #
> -# -> { "execute": "block-latency-histogram-set",
> +# -> { "execute": "block-histogram-set",
>   #      "arguments": { "id": "drive0",
> +#                     "type":"latency",
>   #                     "boundaries": [10, 50, 100] } }
>   # <- { "return": {} }
>   #
> -# Example: set new histogram only for write, other histograms will remain
> -# not changed (or not created):
> +# Example: set new latency histogram only for write, other histograms will
> +# remain not changed (or not created):
>   #
> -# -> { "execute": "block-latency-histogram-set",
> +# -> { "execute": "block-histogram-set",
>   #      "arguments": { "id": "drive0",
> +#                     "type":"latency",
>   #                     "boundaries-write": [10, 50, 100] } }
>   # <- { "return": {} }
>   #
> @@ -613,20 +628,23 @@
>   #   read, flush: [0, 10), [10, 50), [50, 100), [100, +inf)
>   #   write: [0, 1000), [1000, 5000), [5000, +inf)
>   #
> -# -> { "execute": "block-latency-histogram-set",
> +# -> { "execute": "block-histogram-set",
>   #      "arguments": { "id": "drive0",
> +#                     "type":"latency",
>   #                     "boundaries": [10, 50, 100],
>   #                     "boundaries-write": [1000, 5000] } }
>   # <- { "return": {} }
>   #
>   # Example: remove all latency histograms:
>   #
> -# -> { "execute": "block-latency-histogram-set",
> -#      "arguments": { "id": "drive0" } }
> +# -> { "execute": "block-histogram-set",
> +#      "arguments": { "id": "drive0"
> +#                     "type":"latency"} }
>   # <- { "return": {} }
>   ##
> -{ 'command': 'block-latency-histogram-set',
> +{ 'command': 'block-histogram-set',
>     'data': {'id': 'str',
> +           'type': 'BlockHistogramType',
>              '*boundaries': ['uint64'],
>              '*boundaries-read': ['uint64'],
>              '*boundaries-write': ['uint64'],
> @@ -912,11 +930,11 @@
>   # @timed_stats: Statistics specific to the set of previously defined
>   #               intervals of time (Since 2.5)
>   #
> -# @rd_latency_histogram: @BlockLatencyHistogramInfo. (Since 4.0)
> +# @rd_latency_histogram: @BlockHistogramInfo. (Since 4.1)
>   #
> -# @wr_latency_histogram: @BlockLatencyHistogramInfo. (Since 4.0)
> +# @wr_latency_histogram: @BlockHistogramInfo. (Since 4.1)
>   #
> -# @flush_latency_histogram: @BlockLatencyHistogramInfo. (Since 4.0)
> +# @flush_latency_histogram: @BlockHistogramInfo. (Since 4.1)
>   #
>   # Since: 0.14.0
>   ##
> @@ -931,9 +949,12 @@
>              'invalid_wr_operations': 'int', 'invalid_flush_operations': 'int',
>              'account_invalid': 'bool', 'account_failed': 'bool',
>              'timed_stats': ['BlockDeviceTimedStats'],
> -           '*rd_latency_histogram': 'BlockLatencyHistogramInfo',
> -           '*wr_latency_histogram': 'BlockLatencyHistogramInfo',
> -           '*flush_latency_histogram': 'BlockLatencyHistogramInfo' } }
> +           '*rd_latency_histogram': 'BlockHistogramInfo',
> +           '*wr_latency_histogram': 'BlockHistogramInfo',
> +           '*flush_latency_histogram': 'BlockHistogramInfo',
> +           '*rd_size_histogram': 'BlockHistogramInfo',
> +           '*wr_size_histogram': 'BlockHistogramInfo',
> +           '*flush_size_histogram': 'BlockHistogramInfo' } }
>   
>   ##
>   # @BlockStats:
> 


-- 
Best regards,
Vladimir

[Qemu-devel] [PATCH V2 0/3] Add block size histogram qapi interface

[zhenwei pi]

Modify command 'block-latency-histogram-set' to make block histogram
interface common to use. And support block size histogram.
Thanks to Eric Blake&Vladimir Sementsov-Ogievskiy for the suggestions.

This command has been tested for half year on QEMU-2.12, and we found
that 3K+ virtual machines write 25GB/s totally, the block size
histogram like following:
        0 ~ 8k: 58% ~ 62%
        8k ~ 32k: 10% ~ 12%
        32k ~ 128k: 2% ~ 3%
        128K ~ 512K: 24% ~ 26%
        512K ~ : ...

And the histogram data help us to optimise backend distributed
storage.

zhenwei pi (3):
  block/accounting: rename struct BlockLatencyHistogram
  block/accounting: introduce block size histogram
  qapi: make block histogram interface common

 block/accounting.c         |  62 ++++++++++++++++++++--------
 block/qapi.c               |  32 ++++++++------
 blockdev.c                 |  33 +++++++++++----
 include/block/accounting.h |  13 +++---
 qapi/block-core.json       | 101 +++++++++++++++++++++++++++------------------
 5 files changed, 158 insertions(+), 83 deletions(-)

-- 
2.11.0

[Qemu-devel] [PATCH V2 2/3] block/accounting: introduce block size histogram

[zhenwei pi]

Introduce block size histogram statics for block devices.

For read/write/flush operation type, the block size region
[0, +inf) is divided into subregions by several points.
It works like block latency histogram.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/accounting.c         | 18 ++++++++++++++++++
 include/block/accounting.h |  5 ++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/block/accounting.c b/block/accounting.c
index d210a73fe9..3a1e41a971 100644
--- a/block/accounting.c
+++ b/block/accounting.c
@@ -192,6 +192,22 @@ void block_latency_histograms_clear(BlockAcctStats *stats)
     }
 }
 
+int block_size_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
+                             uint64List *boundaries)
+{
+    BlockHistogram *hist = &stats->size_histogram[type];
+
+    return block_histogram_set(hist, boundaries);
+}
+
+void block_size_histograms_clear(BlockAcctStats *stats)
+{
+    int i;
+
+    for (i = 0; i < BLOCK_MAX_IOTYPE; i++) {
+        block_histogram_clear(&stats->size_histogram[i]);
+    }
+}
 static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
                                  bool failed)
 {
@@ -216,6 +232,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
 
     block_histogram_account(&stats->latency_histogram[cookie->type],
                             latency_ns);
+    block_histogram_account(&stats->size_histogram[cookie->type],
+                            cookie->bytes);
 
     if (!failed || stats->account_failed) {
         stats->total_time_ns[cookie->type] += latency_ns;
diff --git a/include/block/accounting.h b/include/block/accounting.h
index 270fddb69c..0fbba64408 100644
--- a/include/block/accounting.h
+++ b/include/block/accounting.h
@@ -89,6 +89,7 @@ struct BlockAcctStats {
     bool account_invalid;
     bool account_failed;
     BlockHistogram latency_histogram[BLOCK_MAX_IOTYPE];
+    BlockHistogram size_histogram[BLOCK_MAX_IOTYPE];
 };
 
 typedef struct BlockAcctCookie {
@@ -117,5 +118,7 @@ double block_acct_queue_depth(BlockAcctTimedStats *stats,
 int block_latency_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
                                 uint64List *boundaries);
 void block_latency_histograms_clear(BlockAcctStats *stats);
-
+int block_size_histogram_set(BlockAcctStats *stats, enum BlockAcctType type,
+                             uint64List *boundaries);
+void block_size_histograms_clear(BlockAcctStats *stats);
 #endif
-- 
2.11.0