Allow a region to collect a latency histogram of flushes.
https://virtuozzo.atlassian.net/browse/VSTOR-103846
Signed-off-by: Andrey Zhadchenko <[email protected]>
---
.../admin-guide/device-mapper/statistics.rst | 11 +++++++++--
drivers/md/dm-stats.c | 10 +++++++++-
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/device-mapper/statistics.rst
b/Documentation/admin-guide/device-mapper/statistics.rst
index 99b8ad45d47fd..ce02fd8a2873d 100644
--- a/Documentation/admin-guide/device-mapper/statistics.rst
+++ b/Documentation/admin-guide/device-mapper/statistics.rst
@@ -101,6 +101,12 @@ Messages
wr_histogram:n1,n2,n3,n4,...
collect a latency histogram like "histogram", but only
account write requests.
+ flush_histogram:n1,n2,n3,n4,...
+ collect a latency histogram like "histogram", but only
+ account data-less cache flushes. Since a data-less
+ flush is not directed at any particular sector, it is
+ accounted in the first step-sized area of the region
+ and does not modify any other counters.
Multiple histogram arguments may be specified for one region;
each histogram is reported as an additional counter set in the
@stats_print output, in the order the histograms were specified.
@@ -148,8 +154,9 @@ Messages
precise_timestamps hist_total_latency histogram:n1,n2,n3,...
The strings "precise_timestamps", "hist_total_latency" and
- "histogram" (also "rd_histogram" and "wr_histogram") are printed
- only if they were specified when creating the region.
+ "histogram" (also "rd_histogram", "wr_histogram" and
+ "flush_histogram") are printed only if they were specified when
+ creating the region.
@stats_print <region_id> [<starting_line> <number_of_lines>]
Print counters for each step-sized area of a region.
diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 4e6667322c0a2..3a0d80bbf78da 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -53,7 +53,7 @@ enum {
#define DM_STAT_CLASSES_DATA ((1 << DM_STAT_CLASS_READ) | \
(1 << DM_STAT_CLASS_WRITE))
-#define DM_STAT_MAX_HISTOGRAMS 3
+#define DM_STAT_MAX_HISTOGRAMS 4
struct dm_stat_histogram {
unsigned int class_mask; /* classes this histogram accounts */
@@ -548,6 +548,8 @@ static const char *dm_stat_histogram_name(unsigned int
class_mask)
return "rd_histogram";
case 1 << DM_STAT_CLASS_WRITE:
return "wr_histogram";
+ case 1 << DM_STAT_CLASS_FLUSH:
+ return "flush_histogram";
default:
return "histogram";
}
@@ -1239,6 +1241,12 @@ static int message_stats_create(struct mapped_device *md,
a + 13);
if (r)
goto ret;
+ } else if (!strncasecmp(a, "flush_histogram:", 16)) {
+ r = add_histogram(histograms, &n_histograms,
+ 1 << DM_STAT_CLASS_FLUSH,
+ a + 16);
+ if (r)
+ goto ret;
} else
goto ret_einval;
}
--
2.43.5
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