Thanks for the quick reply...notes below: On Wed, Dec 17, 2008 at 1:10 PM, David Howells <dhowells@xxxxxxxxxx> wrote: > John Groves <John@xxxxxxxxxx> wrote: > > > The main constraint is that I'm stuck, for now, with EL5 kernels due to > > copious dependencies in the Lustre 1.6.* source base. This is a big > issue, > > but it looks like it should not be a deal breaker. I'm currently running > > kernel 2.6.18-53.1.14. > > Where did you get your fscache kernel patches from? I'm just using the fscache code that was in the stock kernel. > The ones that come built in to the RHEL-5 kernel are unstable. The newer > ones > are much better, but probably not usable with RHEL-5. doh! > > fscache / cachefiles works when /var/fscache is just a directory on my > boot > > drive (ext3). That's nice, but my boot drive is not faster than my > network > > (I can stream about 700MB/s over infiniband, and my lustre object servers > > can keep up with that). My boot drive is good for about 60MB/s. > > Yeah. Caching NFS that's coming over GigE is a complete waste of time if > you're just looking for performance enhancements in what I've observed if > there's no conflicting traffic on the wire. In our case there are a lot of factors, and we can use really fast disk for the cache (if that works, which it doesn't at the moment). > > > > - With ext3 on the ramdisk, cachefilesd dies on startup. > > When you say 'dies' does cachefilesd just die, or is there an oops? Is > anything dumped to dmesg? This is all I get in /var/log/messages: Dec 17 12:50:14 violin cachefilesd[5323]: readdir returned unknown type: errno 4 (Interrupted system call) Dec 17 12:50:14 violin kernel: FZ- lustre_fscache_set_cookie 228 0 8241 NOT READ ONLY<6> Dec 17 12:50:14 violin kernel: CacheFiles: File cache on 08:11 unregistering Dec 17 12:50:14 violin kernel: FS-Cache: Withdrawing cache "mycache" (the FZ message is mine). I don't know where else to look. Looking back through the log, cachefilesd sometimes tanked with errno 4 as well. 9 and 4 are the only cachefilesd errors I see. > > Cachefiles came in the kernel, and I installed cachefilesd with yum. > > If it's the RHEL-5 cachefiles, you're probably doomed, unfortunately. I > know > it's unstable, but finding the source of the instability is a pain. The > newer > patches are much better. I really must try backporting them. I might consider trying the back port... Do you have a recommendation as to what patch to start with? Also, might it be easier just to back port cachefiles? I suppose that will be sensitive to the readv/aio_read change, etc. If I could back port a patch that was better, but not complete modern, it might be easier...or does that sound like a mess to you? Thanks, John Groves -- Linux-cachefs mailing list Linux-cachefs@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cachefs
