On Tue, Sep 13, 2016 at 11:06:57AM +0200, Carlos Maiolino wrote: > On Tue, Sep 13, 2016 at 06:28:42PM +1000, Dave Chinner wrote: > > From: Dave Chinner <dchinner@xxxxxxxxxx> > > > > Embedding a switch statement in every btree stats inc/add adds a lot > > of code overhead to the core btree infrastructure paths. Stats are > > supposed to be small and lightweight, but the btree stats have > > become big and bloated as we've added more btrees. It needs fixing > > because the reflink code will just add more overhead again. > > Talking about stats, is there any documentation for that? I was using the log > stats while working on the fail_at_unmount hang, and I couldn't find anything > other than looking into the code to see what each number means. Most XFS stats are documented in PCP. IIRC, this page was originally pulled from the PCP metric info but is now (like most stuff in wikis) is out of date: http://xfs.org/index.php/Runtime_Stats $ pminfo -T xfs.log xfs.log.writes Help: This variable counts the number of log buffer writes going to the physical log partitions of all XFS filesystems. Log data traffic is proportional to the level of meta-data updating. Log buffer writes get generated when they fill up or external syncs occur. xfs.log.blocks Help: This variable counts the number of Kbytes of information being written to the physical log partitions of all XFS filesystems. Log data traffic is proportional to the level of meta-data updating. The rate with which log data gets written depends on the size of internal log buffers and disk write speed. Therefore, filesystems with very high meta-data updating may need to stripe the log partition or put the log partition on a separate drive. xfs.log.write_ratio Help: The ratio of log blocks written to log writes. If block count isn't a "reasonable" multiple of writes, then many small log writes are being performed - this is suboptimal. Perfection is 64. Fine-grain control can be obtained when this metric is used in conjuntion with pmstore(1) and the xfs.control.reset metric. xfs.log.noiclogs Help: This variable keeps track of times when a logged transaction can not get any log buffer space. When this occurs, all of the internal log buffers are busy flushing their data to the physical on-disk log. xfs.log.force Help: The number of times the in-core log is forced to disk. It is equivalent to the number of successful calls to the function xfs_log_force(). xfs.log.force_sleep Help: This metric is exported from the xs_log_force_sleep field of struct xfsstats -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
