Date: Sat, 23 Nov 2013 22:15:28 -0500 From: Eitan Adler <lists@eitanadler.com> To: Thomas Steen Rasmussen <thomas@gibfest.dk> Cc: "freebsd-fs@freebsd.org" <fs@freebsd.org> Subject: Re: ZFS (or something) is absurdly slow Message-ID: <CAF6rxgkPVDnmS1RTugLVYUP3H6=Azjx%2BsgYv91_6d0yAg6Gthw@mail.gmail.com> In-Reply-To: <5290E0CF.20704@gibfest.dk> References: <CAF6rxgmepSN9pFPH%2BQiLaNqhzXxkXwu=59zvfD-6gGEMg9zh1g@mail.gmail.com> <5290E0CF.20704@gibfest.dk>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sat, Nov 23, 2013 at 12:07 PM, Thomas Steen Rasmussen <thomas@gibfest.dk> wrote: > 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, Nothing unexpected here though I will pay attention during the slow times. > 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 I can run this script, what output should I be looking for? > 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 ? tps stays between 0 and 30 or so. I rarely if ever seen numbers above 30 (This is a consumer grade laptop HDD). tty ada0 ada1 cd0 cpu tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id 25 1144 6.88 5 0.03 13.76 35 0.46 0.00 0 0.00 1 4 2 0 93 -- Eitan Adler
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAF6rxgkPVDnmS1RTugLVYUP3H6=Azjx%2BsgYv91_6d0yAg6Gthw>