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path: root/Documentation/device-mapper/statistics.txt
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2016-05-05dm stats: fix spelling mistake in DocumentationEric Engestrom
Signed-off-by: Eric Engestrom <eric@engestrom.ch> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-08-18dm stats: report precise_timestamps and histogram in @stats_list outputMikulas Patocka
If the user selected the precise_timestamps or histogram options, report it in the @stats_list message output. If the user didn't select these options, no extra tokens are reported, thus it is backward compatible with old software that doesn't know about precise timestamps and histogram. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # 4.2
2015-06-17dm stats: collect and report histogram of IO latenciesMikulas Patocka
Add an option to dm statistics to collect and report a histogram of IO latencies. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-06-17dm stats: support precise timestampsMikulas Patocka
Make it possible to use precise timestamps with nanosecond granularity in dm statistics. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2013-09-05dm: add statistics supportMikulas Patocka
Support the collection of I/O statistics on user-defined regions of a DM device. If no regions are defined no statistics are collected so there isn't any performance impact. Only bio-based DM devices are currently supported. Each user-defined region specifies a starting sector, length and step. Individual statistics will be collected for each step-sized area within the range specified. The I/O statistics counters for each step-sized area of a region are in the same format as /sys/block/*/stat or /proc/diskstats but extra counters (12 and 13) are provided: total time spent reading and writing in milliseconds. All these counters may be accessed by sending the @stats_print message to the appropriate DM device via dmsetup. The creation of DM statistics will allocate memory via kmalloc or fallback to using vmalloc space. At most, 1/4 of the overall system memory may be allocated by DM statistics. The admin can see how much memory is used by reading /sys/module/dm_mod/parameters/stats_current_allocated_bytes See Documentation/device-mapper/statistics.txt for more details. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>