Got a request to add I/O statistics for DM devices, so they will show up when running the iostat command, so I wrote up this patch. The code was taken from the various MD personalities. As such, it only keeps track of the number of reads/writes and the number of sectors read/written. It doesn't keep track of any of the time-based measurements. See struct disk_stats in include/linux/genhd.h for more details. -- Kevin Corry kevcorry@xxxxxxxxxx http://www.ibm.com/linux/ http://evms.sourceforge.net/ Add I/O statistics for Device-Mapper devices. Only keeps track of count and size of I/Os, not completion times. Patch is against 2.6.12. --- diff/drivers/md/dm.c 2005-08-25 11:29:04.000000000 -0500 +++ source/drivers/md/dm.c 2005-08-25 11:26:49.000000000 -0500 @@ -570,6 +570,14 @@ down_read(&md->lock); + if (bio_data_dir(bio) == WRITE) { + disk_stat_inc(dm_disk(md), writes); + disk_stat_add(dm_disk(md), write_sectors, bio_sectors(bio)); + } else { + disk_stat_inc(dm_disk(md), reads); + disk_stat_add(dm_disk(md), read_sectors, bio_sectors(bio)); + } + /* * If we're suspended we have to queue * this io for later.
