I wanted to bring up an issue with Ceph's use of tcmalloc. I know that in Ubuntu (12.04) Ceph uses the distro version of tcmalloc which older. I've personally ran into issues with tcmalloc for our application where the amount of private space for our application (analytics database) is listed in 10s of gigs but the heap profiler only reports a couple hundreds megs of use. It seams like tcmalloc while fast does a poor job with fragmentation. In most cases I rather leave more memory to the OS to cache disk data leave it in case the app needs to use it. I've observed issues with the MDS when it's grown to a few gigs and it doesn't grow down even after I've removed a 2/3 of the tree. It's possible that this is fixed in newer versions of tcmalloc (https://code.google.com/p/gperftools/issues/detail?id=368). I was curious if anyone else audited this / ran into similar issues and bring it up. For us, we moved to jemalloc which does a fine job returning the memory back to the OS. -- Milosz Tanski CTO 10 East 53rd Street, 37th floor New York, NY 10022 p: 646-253-9055 e: milosz@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
