Date: Mon, 11 Sep 2023 17:03:03 +1200 From: Jonathan Chen <jonc@chen.org.nz> To: Garrett Wollman <wollman@bimajority.org> Cc: freebsd-stable@freebsd.org Subject: Re: Did something change with ZFS and vnode caching? Message-ID: <9c818d6e-e1d1-fae2-2dc6-6d472d837c60@chen.org.nz> In-Reply-To: <25853.10676.45028.623279@hergotha.csail.mit.edu> References: <25827.33600.611577.665054@hergotha.csail.mit.edu> <25831.30103.446606.733311@hergotha.csail.mit.edu> <25840.58487.468791.344785@hergotha.csail.mit.edu> <CAGudoHGX5yShLqkOby7_X%2B=aeA_evqvLU-u1d6OiSMuX4jAhyg@mail.gmail.com> <25853.10676.45028.623279@hergotha.csail.mit.edu>
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Hi, On 10/09/23 14:28, Garrett Wollman wrote: > <<On Fri, 1 Sep 2023 01:04:56 +0200, Mateusz Guzik <mjguzik@gmail.com> said: > >> zfs lock arrays are a known problem, bumping them is definitely an option. > > This is the thing I tried next. It took a few attempts (mostly I > think due to my errors) but I'm now running with 512 (instead of 64) > and plan to deploy 1024 soon, as the results are significant: while we > still see significant loads and kmem pressure during the backup > window, backups are able to complete some 5 to 8 hours sooner, and > nfsd remains responsive. How did you bump up the zfs lock array value? Is this a sysctl-tweakable value? I'm currently running a recent version of stable/13 on a 24-CPU machine. It runs Postgresql 15. If I slam the system with a "pg_restore -j 20 ...", the system will freeze more often than not. This issue does not seem to appear if I use UFS as my backing store, so I'm left to assume that it's ZFS related. I'm wondering whether your tweaks will affect my system's behaviour. Cheers. -- Jonathan Chen <jonc@chen.org.nz>help
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