Messages in this thread | | | Date | Mon, 12 Dec 2005 12:16:39 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] vm: enhance __alloc_pages to prioritize pagecache eviction when pressed for memory |
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Neil Horman <nhorman@tuxdriver.com> wrote: > > On Fri, Dec 09, 2005 at 04:29:01PM -0800, Andrew Morton wrote: > > Neil Horman <nhorman@tuxdriver.com> wrote: > > > > > > Hey all- > > > I was recently shown this issue, wherein, if the kernel was kept full of > > > pagecache via applications that were constantly writing large amounts of data to > > > disk, the box could find itself in a position where the vm, in __alloc_pages > > > would invoke the oom killer repetatively within try_to_free_pages, until such > > > time as the box had no candidate processes left to kill, at which point it would > > > panic. > > > > That's pretty bad. Are you able to provide a description which would permit > > others to reproduce this? > > As promised, heres the reproducer that was given to me, and used to reproduce > this problem: > > 1) setup an nfs serve with a thread count of 2. Of course, 1 thread might make > the problem more easy to reproduce. I haven't tried it yet. > > 2) Setup 4 nodes to hammer the nfs mounted directory. The 4 nodes should hammer > out 4 gigs. 2 gigs didn't seem to be enough. > > I used a locally developed tool called ior to reproduce this problem. The tool > can be found here: > > http://www.llnl.gov/asci/platforms/purple/rfp/benchmarks/limited/ior/ > > I suppose anything that can write to NFS fast should be fine. But that's what I > did. > > > If you do this, any node writing to the server that has more than 4GB of RAM > should start oom killing to the point where it runs out of candidate processes > and panics
We merged an NFS fix last week which will help throttling under heavy writeout conditions.. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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