On Tue, Apr 24, 2012 at 1:58 AM, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Mon, Apr 23, 2012 at 05:33:40PM +0200, Juerg Haefliger wrote: >> Hi Dave, >> >> >> On Mon, Apr 23, 2012 at 4:38 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote: >> > On Mon, Apr 23, 2012 at 02:09:53PM +0200, Juerg Haefliger wrote: >> >> Hi, >> >> >> >> I have a test system that I'm using to try to force an XFS filesystem >> >> hang since we're encountering that problem sporadically in production >> >> running a 2.6.38-8 Natty kernel. The original idea was to use this >> >> system to find the patches that fix the issue but I've tried a whole >> >> bunch of kernels and they all hang eventually (anywhere from 5 to 45 >> >> mins) with the stack trace shown below. >> > >> > If you kill the workload, does the file system recover normally? >> >> The workload can't be killed. > > OK. > >> >> Only an emergency flush will >> >> bring the filesystem back. I tried kernels 3.0.29, 3.1.10, 3.2.15, >> >> 3.3.2. From reading through the mail archives, I get the impression >> >> that this should be fixed in 3.1. >> > >> > What you see is not necessarily a hang. It may just be that you've >> > caused your IO subsystem to have so much IO queued up it's completely >> > overwhelmed. How much RAM do you have in the machine? >> >> When it hangs, there are zero IOs going to the disk. The machine has >> 100GB of RAM. > > Can you get an event trace across the period where the hang occurs? > > .... > >> >> I can't seem to hit the problem without the above modifications. >> > >> > How on earth did you come up with this configuration? >> >> Just plain ol' luck. I was looking for a configuration that would >> allow me to reproduce the hangs and I accidentally picked a machine >> with a faulty controller battery which disabled the cache. > > Wonderful. > >> >> For the IO workload I pre-create 8000 files with random content and >> >> sizes between 1k and 128k on the test partition. Then I run a tool >> >> that spawns a bunch of threads which just copy these files to a >> >> different directory on the same partition. >> > >> > So, your workload also has a significant amount parallelism and >> > concurrency on a filesytsem with only 4 AGs? >> >> Yes. Excuse my ignorance but what are AGs? > > Allocation groups. > >> >> At the same time there are >> >> other threads that rename, remove and overwrite random files in the >> >> destination directory keeping the file count at around 500. >> > >> > And you've added as much concurrent metadata modification as >> > possible, too, which makes me wonder..... >> > >> >> Let me know what other information I can provide to pin this down. >> > >> > .... exactly what are you trying to acheive with this test? From my >> > point of view, you're doing something completely and utterly insane. >> > You filesystem config and workload is so far outside normal >> > configurations and workloads that I'm not surprised you're seeing >> > some kind of problem..... >> >> No objection from my side. It's a silly configuration but it's the >> only one I've found that lets me reproduce a hang at will. > > Ok, that's fair enough - it's handy to tell us that up front, > though. ;) Ah sorry for not being clear enough. I thought my intentions could be deduced from the information that I provided :-) > Alright, then I need all the usual information. I suspect an event > trace is the only way I'm going to see what is happening. I just > updated the FAQ entry, so all the necessary info for gathering a > trace should be there now. > > http://xfs.org/index.php/XFS_FAQ#Q:_What_information_should_I_include_when_reporting_a_problem.3F Very good. Will do. What kernel do you want me to run? I would prefer our current production kernel (2.6.38-8-server) but I understand if you want something newer. ...Juerg > -- > Dave Chinner > david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
