Commit 7e5c776d authored by Vladimir Sementsov-Ogievskiy's avatar Vladimir Sementsov-Ogievskiy Committed by Eric Blake
Browse files

qapi: add block latency histogram interface 



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: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20180309165212.97144-3-vsementsov@virtuozzo.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
[eblake: fix typos, mention x- prefix in commit message]
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent b741ae74

block/qapi.c

+41 −0
Original line number Diff line number Diff line
@@ -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,

blockdev.c

+43 −0
Original line number Diff line number Diff line
@@ -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),

qapi/block-core.json

+110 −1
Original line number Diff line number Diff line
@@ -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: