On Tue, May 29, 2012 at 12:44 AM, Amon Ott <a.ott@xxxxxxxxxxxx> wrote: > On Linux, if you run OSD on ext4 filesystem, have a cephfs kernel client mount > on the same system and no syncfs system call (as to be expected with libc6 < > 2.14 or kernel < 2.6.39), OSD deadlocks in sys_sync(). Only reboot recovers > the system. This is the classic issue of memory pressure needing free memory to be relieved. While syncfs(2) may make the hang less common, I do not think having syncfs(2) is enough; nothing sort of having a reserved memory pool guaranteed to be big enough to handle the request will, and maintaining that solution is hideously complex. Loopback NFS suffers from the exact same thing. Apparently using ceph-fuse is enough to move so much of the processing to user space, that the pageability of userspace memory allows the system to recover. Here's a fragment of the earlier conversation on this topic. Apologies for gmane/mail clients breaking the thread, anything with that subject line is part of the conversation: http://thread.gmane.org/gmane.comp.file-systems.ceph.devel/1673 -- 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
