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qapi: add block latency histogram interface

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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>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2018-03-09 19:52:12 +03:00 committed by Eric Blake
parent b741ae7417
commit 7e5c776d15
3 changed files with 194 additions and 1 deletions
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41
block/qapi.c
View File

@ -394,6 +394,37 @@ 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,
BlockLatencyHistogramInfo **info)
{
*not_null = hist->bins != NULL;
if (*not_null) {
*info = g_new0(BlockLatencyHistogramInfo, 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);
@ -459,6 +490,16 @@ 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,

43
blockdev.c
View File

@ -4239,6 +4239,49 @@ void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
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),

111
qapi/block-core.json
View File

@ -453,6 +453,106 @@
'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32',
'status': 'DirtyBitmapStatus'} }
##
# @BlockLatencyHistogramInfo:
#
# 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': 'BlockLatencyHistogramInfo',
'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
# 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).
#
# @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-write: list of interval boundary values for write latency
# histogram.
#
# @boundaries-flush: list of interval boundary values for flush latency
# histogram.
#
# Returns: error if device is not found or any boundary 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:
#
@ -733,6 +833,12 @@
# @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',
@ -745,7 +851,10 @@
'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': 'BlockLatencyHistogramInfo',
'*x_wr_latency_histogram': 'BlockLatencyHistogramInfo',
'*x_flush_latency_histogram': 'BlockLatencyHistogramInfo' } }
##
# @BlockStats: