On 9/26/2013 9:23 AM, Eric Sandeen wrote: > On 9/26/13 8:30 AM, Ronnie Tartar wrote: >> Stan, looks like I have directory fragmentation problem. >> >> xfs_db> frag -d >> actual 65057, ideal 4680, fragmentation factor 92.81% >> >> What is the best way to fix this? > > http://xfs.org/index.php/XFS_FAQ#Q:_The_xfs_db_.22frag.22_command_says_I.27m_over_50.25._Is_that_bad.3F > > We should just get rid of that command, TBH. > > So your dirs are in an average of 65057/4680 or about 14 fragments each. > Really not that bad, in the scope of things. > > I'd imagine that this could be more of your problem: > >> The >> folders are image folders that have anywhere between 5 to 10 million images >> in each folder. > > at 10 million entries in a dir, you're going to start slowing down on inserts > due to btree management. But that probably doesn't account for multiple seconds for > a single file. > > So really,it's not clear *what* is slow. > >> It takes about 2.5 to 3.5 seconds to write a single file. > > strace with timing would be a very basic way to get a sense of what is slow; > is it the file open/create? How big is the file, are you doing buffered or > direct IO? > > On a more modern OS you could do some of the tracing suggested in > http://xfs.org/index.php/XFS_FAQ#Q:_What_information_should_I_include_when_reporting_a_problem.3F > > but some sort of profiling (oprofile, perhaps) might tell you where time is being spent in the kernel. > > When you say suddenly started, was it after a kernel upgrade or other change? Eric is an expert on this, much more knowledgeable than me. And somehow I missed the 5-10 million files per dir. Maybe you have multiple issues here adding up to large delays. In addition to the steps Eric recommends, it can't hurt to go ahead and take a look at the free space map. Depending on how the filesystem has aged this could be a factor, such as being 90%+ full at one time, and then lots of files being deleted. # xfs_db -r -c freesp /dev/[device] -- Stan _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
