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Diffstat (limited to 'Documentation/block/stat.txt')
| -rw-r--r-- | Documentation/block/stat.txt | 86 |
1 files changed, 0 insertions, 86 deletions
diff --git a/Documentation/block/stat.txt b/Documentation/block/stat.txt deleted file mode 100644 index 0aace9cc536c..000000000000 --- a/Documentation/block/stat.txt +++ /dev/null @@ -1,86 +0,0 @@ -Block layer statistics in /sys/block/<dev>/stat -=============================================== - -This file documents the contents of the /sys/block/<dev>/stat file. - -The stat file provides several statistics about the state of block -device <dev>. - -Q. Why are there multiple statistics in a single file? Doesn't sysfs - normally contain a single value per file? -A. By having a single file, the kernel can guarantee that the statistics - represent a consistent snapshot of the state of the device. If the - statistics were exported as multiple files containing one statistic - each, it would be impossible to guarantee that a set of readings - represent a single point in time. - -The stat file consists of a single line of text containing 11 decimal -values separated by whitespace. The fields are summarized in the -following table, and described in more detail below. - -Name units description ----- ----- ----------- -read I/Os requests number of read I/Os processed -read merges requests number of read I/Os merged with in-queue I/O -read sectors sectors number of sectors read -read ticks milliseconds total wait time for read requests -write I/Os requests number of write I/Os processed -write merges requests number of write I/Os merged with in-queue I/O -write sectors sectors number of sectors written -write ticks milliseconds total wait time for write requests -in_flight requests number of I/Os currently in flight -io_ticks milliseconds total time this block device has been active -time_in_queue milliseconds total wait time for all requests -discard I/Os requests number of discard I/Os processed -discard merges requests number of discard I/Os merged with in-queue I/O -discard sectors sectors number of sectors discarded -discard ticks milliseconds total wait time for discard requests - -read I/Os, write I/Os, discard I/0s -=================================== - -These values increment when an I/O request completes. - -read merges, write merges, discard merges -========================================= - -These values increment when an I/O request is merged with an -already-queued I/O request. - -read sectors, write sectors, discard_sectors -============================================ - -These values count the number of sectors read from, written to, or -discarded from this block device. The "sectors" in question are the -standard UNIX 512-byte sectors, not any device- or filesystem-specific -block size. The counters are incremented when the I/O completes. - -read ticks, write ticks, discard ticks -====================================== - -These values count the number of milliseconds that I/O requests have -waited on this block device. If there are multiple I/O requests waiting, -these values will increase at a rate greater than 1000/second; for -example, if 60 read requests wait for an average of 30 ms, the read_ticks -field will increase by 60*30 = 1800. - -in_flight -========= - -This value counts the number of I/O requests that have been issued to -the device driver but have not yet completed. It does not include I/O -requests that are in the queue but not yet issued to the device driver. - -io_ticks -======== - -This value counts the number of milliseconds during which the device has -had I/O requests queued. - -time_in_queue -============= - -This value counts the number of milliseconds that I/O requests have waited -on this block device. If there are multiple I/O requests waiting, this -value will increase as the product of the number of milliseconds times the -number of requests waiting (see "read ticks" above for an example). |