Pawel, I don't understand the connection with the ZIL, the referenced bug has no ZIL path. I think that deserves more investigation.
Also, please don't ship ZFS with the ZIL disabled. That would remove POSIX compliance as fsync, O_DSYNC and friends are not working. Applications that make use of these may generate corrupt files. Also users will complain when perf decreases when the ZIL is re-enabled! Thanks: Neil. Pawel Jakub Dawidek wrote: > On Fri, May 18, 2007 at 08:22:26AM -0600, Mark Maybee wrote: >> Yup, J?rgen is correct. The problem here is that we are blocked in >> arc_data_buf_alloc() while holding a hash_lock. This is bug 6457639. >> One possibility, for this specific bug might be to drop the lock before >> the allocate and then redo the read lookup (in case there is a race) >> with the necessary buffer already in hand. > > Any updates on this? We don't see those deadlocks when ZIL is disabled > and we're thinking about disabling ZIL by default for 7.0-RELEASE if we > won't find fix for this. It is somehow quite easy to triggers for some > workloads. > >> J?rgen Keil wrote: >>>> Kris Kennaway <kris at FreeBSD.org> found a deadlock, >>>> which I think is not FreeBSD-specific. >>>> >>>> When we are running low in memory and kmem_alloc(KM_SLEEP) is called, >>>> the thread waits for the memory to be reclaimed, right? >>>> In such situation the arc_reclaim_thread thread is woken up. >>>> >>>> Ok. I've two threads waiting for the memory to be freed: >>>> >>>> First one, and this one is not really problematic: >>> ... >>>> And second one, which holds >>>> arc_buf_t->b_hdr->hash_lock: >>> >>> Bug 6457639 might be related, >>> http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6457639 >>> >>> In this case I also found the arc deadlocking because of KM_SLEEP >>> allocations, while having parts of the buf hash table locked. > > > ------------------------------------------------------------------------ > > _______________________________________________ > zfs-code mailing list > zfs-code at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-code
