Date: Fri, 22 Jan 2016 11:34:17 -0500 From: Mason Loring Bliss <mason@blisses.org> To: Warren Block <wblock@wonkity.com>, freebsd-questions@freebsd.org, kpneal@pobox.com, markham breitbach <markhamb@corp.ssimicro.com>, Priyadarshan <bsd@bontempi.net> Subject: Re: ZFS performance help sought Message-ID: <20160122163417.GS4538@blisses.org> In-Reply-To: <1453455663.2364898.499431058.4EA85780@webmail.messagingengine.com> <56A24D25.70206@corp.ssimicro.com> <20160122135452.GC12085@neutralgood.org> <20160122140549.053fea0f@fabiankeil.de> <alpine.BSF.2.20.1601212315400.85472@wonkity.com>
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On Thu, Jan 21, 2016 at 11:17:05PM -0700, Warren Block wrote: > I know there was some sort of ZFS resource exhaustion issue worked on > recently, but I don't recally exactly when or what the symptoms were. It > might only be in 10-stable so far. Best to ask on the freebsd-fs mailing > list. Thank you. I'm subscribing to that now. > It's conceivable that you are seeing the result of lock contention that > is slowing down arc_get_data_buf(), for details see: > https://www.fabiankeil.de/gehacktes/electrobsd/zfs-arc-tuning/ I will look at that and try the dtrace script soon. Thank you. > Even if it's a different issue, you may be able to work around it by > throttling the send/receive throughput with mbuffer or a similar tool. Most of the time I schedule the bulk moves for hours where I wouldn't notice the system being bogged down, so I'm more interested in identifying it than working around it, but that's worth noting, especially given that there is a very easy chokepoint to be had in the pipeline. On Fri, Jan 22, 2016 at 08:54:52AM -0500, kpneal@pobox.com wrote: > FWIW, I have a machine with a three way mirror, SAS 3Gb, 8GB RAM, and when > mutt saves a roughly 3GB mailbox it pushes the machine into swap. I'll move further correspondence to freebsd-fs once I've confirmed my subscription there, but I'd be curious to know if you can suggest a simple test case there I can reproduce. Is it one big mbox file, as opposed to maildir? Are you deleting a mail from the middle, or doing some other operation? On my end, I take a dataset with maybe 130G in it and I remove it from back-ups, and then re-ship it to tickle the issue. On Fri, Jan 22, 2016 at 08:39:17AM -0700, markham breitbach wrote: > There were some ZFS threads on freebsd-performance a while back too. It > might be worth throwing the question out that way too. Thank you. I will subscribe and look at archives there too. -- Mason Loring Bliss mason@blisses.org Ewige Blumenkraft! awake ? sleep : random() & 2 ? dream : sleep; -- Hamlet, Act III, Scene I
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