On Tue, Feb 26, 2013 at 11:58 AM, Kevin Decherf <[email protected]> wrote: > We have one folder per application (php, java, ruby). Every application has > small (<1M) files. The folder is mounted by only one client by default. > > In case of overload, another clients spawn to mount the same folder and > access the same files. > > In the following test, only one client was used to serve the > application (a website using wordpress). > > I made the test with strace to see the time of each IO request (strace -T > -e trace=file) and I noticed the same pattern: > > ... > [pid 4378] stat("/data/wp-includes/user.php", {st_mode=S_IFREG|0750, > st_size=28622, ...}) = 0 <0.033409> > [pid 4378] lstat("/data/wp-includes/user.php", {st_mode=S_IFREG|0750, > st_size=28622, ...}) = 0 <0.081642> > [pid 4378] open("/data/wp-includes/user.php", O_RDONLY) = 5 <0.041138> > [pid 4378] stat("/data/wp-includes/meta.php", {st_mode=S_IFREG|0750, > st_size=10896, ...}) = 0 <0.082303> > [pid 4378] lstat("/data/wp-includes/meta.php", {st_mode=S_IFREG|0750, > st_size=10896, ...}) = 0 <0.004090> > [pid 4378] open("/data/wp-includes/meta.php", O_RDONLY) = 5 <0.081929> > ... > > ~250 files were accessed for only one request (thanks Wordpress.).
Okay, that is slower than I'd expect, even for an across-the-wire request... > The fs is mounted with these options: > rw,noatime,name=<hidden>,secret=<hidden>,nodcache. What kernel and why are you using nodcache? Did you have problems without that mount option? That's forcing an MDS access for most operations, rather than using local data. > I have a debug (debug_mds=20) log of the active mds during this test if you > want. Yeah, can you post it somewhere? -Greg -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
