* [Qemu-devel] [PATCH v4 1/2] block/accounting: introduce latency histogram
2018-03-09 15:33 [Qemu-devel] [PATCH v4 0/2] block latency histogram Vladimir Sementsov-Ogievskiy
@ 2018-03-09 15:33 ` Vladimir Sementsov-Ogievskiy
2018-03-09 15:33 ` [Qemu-devel] [PATCH v4 2/2] qapi: add block latency histogram interface Vladimir Sementsov-Ogievskiy
2018-03-09 15:40 ` [Qemu-devel] [PATCH v4 0/2] block latency histogram Eric Blake
2 siblings, 0 replies; 7+ messages in thread
From: Vladimir Sementsov-Ogievskiy @ 2018-03-09 15:33 UTC (permalink / raw)
To: qemu-devel, qemu-block
Cc: eblake, armbru, mreitz, kwolf, den, vsementsov, nshirokovskiy
Introduce latency histogram statics for block devices.
For each accounted operation type latency region [0, +inf) is
divided into subregions by several points. Then, calculate
hits for each subregion.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
include/block/accounting.h | 32 +++++++++++++++++++++++++
block/accounting.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 91 insertions(+)
diff --git a/include/block/accounting.h b/include/block/accounting.h
index b833d26d6c..e23951619e 100644
--- a/include/block/accounting.h
+++ b/include/block/accounting.h
@@ -45,6 +45,36 @@ struct BlockAcctTimedStats {
QSLIST_ENTRY(BlockAcctTimedStats) entries;
};
+typedef struct BlockLatencyHistogram {
+ /* The following histogram is represented like this:
+ *
+ * 5| *
+ * 4| *
+ * 3| * *
+ * 2| * * *
+ * 1| * * * *
+ * +------------------
+ * 10 50 100
+ *
+ * BlockLatencyHistogram histogram = {
+ * .nbins = 4,
+ * .boundaries = {10, 50, 100},
+ * .bins = {3, 1, 5, 2},
+ * };
+ *
+ * @boundaries array define histogram intervals as follows:
+ * [0, boundaries[0]), [boundaries[0], boundaries[1]), ...
+ * [boundaries[nbins-2], +inf)
+ *
+ * So, for example above, histogram intervals are:
+ * [0, 10), [10, 50), [50, 100), [100, +inf)
+ */
+ int nbins;
+ uint64_t *boundaries; /* @nbins-1 numbers here
+ (all boundaries, except 0 and +inf) */
+ uint64_t *bins;
+} BlockLatencyHistogram;
+
struct BlockAcctStats {
QemuMutex lock;
uint64_t nr_bytes[BLOCK_MAX_IOTYPE];
@@ -57,6 +87,7 @@ struct BlockAcctStats {
QSLIST_HEAD(, BlockAcctTimedStats) intervals;
bool account_invalid;
bool account_failed;
+ BlockLatencyHistogram latency_histogram[BLOCK_MAX_IOTYPE];
};
typedef struct BlockAcctCookie {
@@ -82,5 +113,6 @@ void block_acct_merge_done(BlockAcctStats *stats, enum BlockAcctType type,
int64_t block_acct_idle_time_ns(BlockAcctStats *stats);
double block_acct_queue_depth(BlockAcctTimedStats *stats,
enum BlockAcctType type);
+void block_latency_histograms_clear(BlockAcctStats *stats);
#endif
diff --git a/block/accounting.c b/block/accounting.c
index 87ef5bbfaa..26a880bc6d 100644
--- a/block/accounting.c
+++ b/block/accounting.c
@@ -94,6 +94,62 @@ void block_acct_start(BlockAcctStats *stats, BlockAcctCookie *cookie,
cookie->type = type;
}
+/* block_latency_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)
+{
+ uint64_t k = *(uint64_t *)key;
+ uint64_t a = ((uint64_t *)it)[0];
+ uint64_t b = ((uint64_t *)it)[1];
+
+ return k < a ? -1 : (k < b ? 0 : 1);
+}
+
+static void block_latency_histogram_account(BlockLatencyHistogram *hist,
+ int64_t latency_ns)
+{
+ uint64_t *pos;
+
+ if (hist->bins == NULL) {
+ /* histogram disabled */
+ return;
+ }
+
+
+ if (latency_ns < hist->boundaries[0]) {
+ hist->bins[0]++;
+ return;
+ }
+
+ if (latency_ns >= hist->boundaries[hist->nbins - 2]) {
+ hist->bins[hist->nbins - 1]++;
+ return;
+ }
+
+ pos = bsearch(&latency_ns, hist->boundaries, hist->nbins - 2,
+ sizeof(hist->boundaries[0]),
+ block_latency_histogram_compare_func);
+ assert(pos != NULL);
+
+ hist->bins[pos - hist->boundaries + 1]++;
+}
+
+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));
+ }
+}
+
static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
bool failed)
{
@@ -116,6 +172,9 @@ 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);
+
if (!failed || stats->account_failed) {
stats->total_time_ns[cookie->type] += latency_ns;
stats->last_access_time_ns = time_ns;
--
2.11.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* [Qemu-devel] [PATCH v4 2/2] qapi: add block latency histogram interface
2018-03-09 15:33 [Qemu-devel] [PATCH v4 0/2] block latency histogram Vladimir Sementsov-Ogievskiy
2018-03-09 15:33 ` [Qemu-devel] [PATCH v4 1/2] block/accounting: introduce " Vladimir Sementsov-Ogievskiy
@ 2018-03-09 15:33 ` Vladimir Sementsov-Ogievskiy
2018-03-09 15:40 ` [Qemu-devel] [PATCH v4 0/2] block latency histogram Eric Blake
2 siblings, 0 replies; 7+ messages in thread
From: Vladimir Sementsov-Ogievskiy @ 2018-03-09 15:33 UTC (permalink / raw)
To: qemu-devel, qemu-block
Cc: eblake, armbru, mreitz, kwolf, den, vsementsov, nshirokovskiy
Set (and clear) histogram through new command
block-latency-histogram-set and show new statistics in
query-blockstats results.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
qapi/block-core.json | 111 ++++++++++++++++++++++++++++++++++++++++++++++++++-
block/qapi.c | 41 +++++++++++++++++++
blockdev.c | 76 +++++++++++++++++++++++++++++++++++
3 files changed, 227 insertions(+), 1 deletion(-)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 8225308904..fd4c13ad8a 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -451,6 +451,106 @@
'status': 'DirtyBitmapStatus'} }
##
+# @XBlockLatencyHistogramInfo:
+#
+# Block latency histogram.
+#
+# @boundaries: list of interval boundary values in nanoseconds, 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).
+#
+# @bins: list of io request counts corresponding to histogram intervals.
+# len(@bins) = len(@boundaries) + 1
+# For the example above, @bins may be something like [3, 1, 5, 2],
+# and corresponding histogram looks like:
+#
+# 5| *
+# 4| *
+# 3| * *
+# 2| * * *
+# 1| * * * *
+# +------------------
+# 10 50 100
+#
+# Since: 2.12
+##
+{ 'struct': 'XBlockLatencyHistogramInfo',
+ 'data': {'boundaries': ['uint64'], 'bins': ['uint64'] } }
+
+##
+# @x-block-latency-histogram-set:
+#
+# Manage read, write and flush latency histograms for the device.
+#
+# If only @device parameter is specified, remove all present latency histograms
+# for the device. Otherwise, add/reset some of (or all) latency histograms.
+#
+# @device: device name to set latency histogram for.
+#
+# @boundaries: list of interval boundary values (see description in
+# XBlockLatencyHistogramInfo 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).
+#
+# @boundaries-read: list of interval boundary values for read latency
+# histogram. If specified, old read latency histogram is
+# removed, and empty one created with interavals
+# corresponding to @boundaries-read. The parameter has higher
+# priority then @boundaries.
+#
+# @boundaries-write: list of interaval boundary values for write latency
+# histogram.
+#
+# @boundaries-flush: list of interaval boundary values for flush latency
+# histogram.
+#
+# Returns: error if device is not found or @boundaries* arrays are invalid.
+#
+# Since: 2.12
+#
+# Example: set new histograms for all io types with intervals
+# [0, 10), [10, 50), [50, 100), [100, +inf):
+#
+# -> { "execute": "block-latency-histogram-set",
+# "arguments": { "device": "drive0",
+# "boundaries": [10, 50, 100] } }
+# <- { "return": {} }
+#
+# Example: set new histogram only for write, other histograms will remain
+# not changed (or not created):
+#
+# -> { "execute": "block-latency-histogram-set",
+# "arguments": { "device": "drive0",
+# "boundaries-write": [10, 50, 100] } }
+# <- { "return": {} }
+#
+# Example: set new histograms with the following intervals:
+# read, flush: [0, 10), [10, 50), [50, 100), [100, +inf)
+# write: [0, 1000), [1000, 5000), [5000, +inf)
+#
+# -> { "execute": "block-latency-histogram-set",
+# "arguments": { "device": "drive0",
+# "boundaries": [10, 50, 100],
+# "boundaries-write": [1000, 5000] } }
+# <- { "return": {} }
+#
+# Example: remove all latency histograms:
+#
+# -> { "execute": "block-latency-histogram-set",
+# "arguments": { "device": "drive0" } }
+# <- { "return": {} }
+##
+{ 'command': 'x-block-latency-histogram-set',
+ 'data': {'device': 'str',
+ '*boundaries': ['uint64'],
+ '*boundaries-read': ['uint64'],
+ '*boundaries-write': ['uint64'],
+ '*boundaries-flush': ['uint64'] } }
+
+##
# @BlockInfo:
#
# Block device information. This structure describes a virtual device and
@@ -730,6 +830,12 @@
# @timed_stats: Statistics specific to the set of previously defined
# intervals of time (Since 2.5)
#
+# @x_rd_latency_histogram: @BlockLatencyHistogramInfo. (Since 2.12)
+#
+# @x_wr_latency_histogram: @BlockLatencyHistogramInfo. (Since 2.12)
+#
+# @x_flush_latency_histogram: @BlockLatencyHistogramInfo. (Since 2.12)
+#
# Since: 0.14.0
##
{ 'struct': 'BlockDeviceStats',
@@ -742,7 +848,10 @@
'failed_flush_operations': 'int', 'invalid_rd_operations': 'int',
'invalid_wr_operations': 'int', 'invalid_flush_operations': 'int',
'account_invalid': 'bool', 'account_failed': 'bool',
- 'timed_stats': ['BlockDeviceTimedStats'] } }
+ 'timed_stats': ['BlockDeviceTimedStats'],
+ '*x_rd_latency_histogram': 'XBlockLatencyHistogramInfo',
+ '*x_wr_latency_histogram': 'XBlockLatencyHistogramInfo',
+ '*x_flush_latency_histogram': 'XBlockLatencyHistogramInfo' } }
##
# @BlockStats:
diff --git a/block/qapi.c b/block/qapi.c
index fc10f0a565..4bddf48e50 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -389,6 +389,37 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
qapi_free_BlockInfo(info);
}
+static uint64List *uint64_list(uint64_t *list, int size)
+{
+ int i;
+ uint64List *out_list = NULL;
+ uint64List **pout_list = &out_list;
+
+ for (i = 0; i < size; i++) {
+ uint64List *entry = g_new(uint64List, 1);
+ entry->value = list[i];
+ *pout_list = entry;
+ pout_list = &entry->next;
+ }
+
+ *pout_list = NULL;
+
+ return out_list;
+}
+
+static void bdrv_latency_histogram_stats(BlockLatencyHistogram *hist,
+ bool *not_null,
+ XBlockLatencyHistogramInfo **info)
+{
+ *not_null = hist->bins != NULL;
+ if (*not_null) {
+ *info = g_new0(XBlockLatencyHistogramInfo, 1);
+
+ (*info)->boundaries = uint64_list(hist->boundaries, hist->nbins - 1);
+ (*info)->bins = uint64_list(hist->bins, hist->nbins);
+ }
+}
+
static void bdrv_query_blk_stats(BlockDeviceStats *ds, BlockBackend *blk)
{
BlockAcctStats *stats = blk_get_stats(blk);
@@ -454,6 +485,16 @@ static void bdrv_query_blk_stats(BlockDeviceStats *ds, BlockBackend *blk)
dev_stats->avg_wr_queue_depth =
block_acct_queue_depth(ts, BLOCK_ACCT_WRITE);
}
+
+ bdrv_latency_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_READ],
+ &ds->has_x_rd_latency_histogram,
+ &ds->x_rd_latency_histogram);
+ bdrv_latency_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_WRITE],
+ &ds->has_x_wr_latency_histogram,
+ &ds->x_wr_latency_histogram);
+ bdrv_latency_histogram_stats(&stats->latency_histogram[BLOCK_ACCT_FLUSH],
+ &ds->has_x_flush_latency_histogram,
+ &ds->x_flush_latency_histogram);
}
static BlockStats *bdrv_query_bds_stats(BlockDriverState *bs,
diff --git a/blockdev.c b/blockdev.c
index 8e977eef11..9d7d56ca81 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -4176,6 +4176,82 @@ void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
aio_context_release(old_context);
}
+static int block_latency_histogram_set(BlockAcctStats *stats,
+ enum BlockAcctType type,
+ uint64List *boundaries)
+{
+ BlockLatencyHistogram *hist = &stats->latency_histogram[type];
+ uint64List *entry;
+ uint64_t *ptr;
+ uint64_t prev = 0;
+ int new_nbins = 1;
+
+ for (entry = boundaries; entry; entry = entry->next) {
+ if (entry->value <= prev) {
+ return -EINVAL;
+ }
+ new_nbins++;
+ prev = entry->value;
+ }
+
+ hist->nbins = new_nbins;
+ g_free(hist->boundaries);
+ hist->boundaries = g_new(uint64_t, hist->nbins - 1);
+ for (entry = boundaries, ptr = hist->boundaries; entry;
+ entry = entry->next, ptr++)
+ {
+ *ptr = entry->value;
+ }
+
+ g_free(hist->bins);
+ hist->bins = g_new0(uint64_t, hist->nbins);
+
+ return 0;
+}
+
+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),
--
2.11.1
^ permalink raw reply related [flat|nested] 7+ messages in thread