Date: Sat, 23 Nov 2013 18:07:27 +0100 From: Thomas Steen Rasmussen <thomas@gibfest.dk> To: Eitan Adler <lists@eitanadler.com> Cc: "freebsd-fs@freebsd.org" <fs@freebsd.org> Subject: Re: ZFS (or something) is absurdly slow Message-ID: <5290E0CF.20704@gibfest.dk> In-Reply-To: <CAF6rxgmepSN9pFPH%2BQiLaNqhzXxkXwu=59zvfD-6gGEMg9zh1g@mail.gmail.com> References: <CAF6rxgmepSN9pFPH%2BQiLaNqhzXxkXwu=59zvfD-6gGEMg9zh1g@mail.gmail.com>
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On 23-11-2013 09:26, Eitan Adler wrote: > Every so often I see absurdly slow tasks stuck on "zio->io_cv". > > For example a recent "git checkout file.c" did not complete for many minutes > load: 0.65 cmd: git 74577 [zio->io_cv] 435.58r 0.20u 2.54s 0% 71488k > > I have seen "ls ~" take tends of minutes to complete. Even "ls > /var/empty" can take just as long. This length of time is variable > but is usually much longer than expected. > > Does anyone have any suggestions for helping to figure out what is > taking a long time? Hello, If "top -m io -o total" doesn't reveal what is using the disks, I've had good experiences with the following dtrace script, you'd need to build dtrace support in your kernel though: vfsstat.d https://forums.freebsd.org/showpost.php?p=182070&postcount=6 You can also check systat -iostast 1 and check the TPS count for the disks. The regular (spinning) harddisk can manage 200-300 iops if it is a regular consumer class disk. Are you "running out" of iops for some reason ? Good luck with it, Best regards Thomas Steen Rasmussen
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