On Wed, 2005-10-19 at 16:52 -0700, Dave Pifke wrote: > I'm doing some performance tweaking on a web server that has a 2TB JFS > partition, and I'm curious about a memory usage pattern I'm seeing with > regards to the Buffer/Cache usage reported in /proc/meminfo. > > The system has 2GB of RAM. At the moment, ~117MB is free, ~1.5GB is > being used for buffers(!), and ~180MB is cached. I'm concerned that the > relatively small amount of disk cache is hurting performance. > > I originally posted this issue to LKML, and Andrew Morton thought it > might be something JFS specific. (lots of metadata in the blockdev > pagecache?) > > The machine uses Apache (mpm_worker) to serve up image files - a third > thumbnails (<1kB), a third resized to the 50-100kB range, and a third > originals (max 1MB). Thumbnails should be getting served much more > frequently than the others, so the disk access pattern is lots of small > files. Directories are hashed year/month/day/hour with maybe 4000 files > in each. The filesystem is mounted with -o noatime and I'm using the > cfq elevator. > > I'm running Debian stable on a dual-Opteron system: > > Linux file003b 2.6.8-11-amd64-k8-smp #1 SMP Wed Jun 1 00:01:27 CEST 2005 > x86_64 GNU/Linux > > slabtop shows ~161MB total size. Far and away the bigest slab users are > buffer_head at ~50MB and radix_tree_node at ~99MB. > > The machine is fairly responsive, but I'm seeing a load average of > between 2 and 3 with about 250 concurrent Apache requests - I'm > obviously hoping for better performance. > > Ideas? Or is this about what one would expect given the system > configuration and workload?
There was a pretty major memory leak in jfs in the 2.6.8 kernel. This one-line fix is in the 2.6.9 kernel. I'm guessing that this would explain the problem you are seeing. http://www.kernel.org/git/gitweb.cgi?p=linux/kernel/git/tglx/history.git;a=commitdiff;h=fcc1fcc376bb1fe8ed7609b07931fc5bd774943a -- David Kleikamp IBM Linux Technology Center ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ Jfs-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jfs-discussion
