Date: Mon, 20 Aug 2012 12:44:11 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-fs@freebsd.org Subject: Re: ZFS scrub CPU bound? Message-ID: <k0t4ds$bt3$1@ger.gmane.org> In-Reply-To: <5023D9B7.20001@digsys.bg> References: <5023D9B7.20001@digsys.bg>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig5CC6457B180713D1070139C7 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 09/08/2012 17:39, Daniel Kalchev wrote: > CPU: 0.4% user, 0.0% nice, 51.4% system, 0.8% interrupt, 47.3% idle > Mem: 2171M Active, 1541M Inact, 5407M Wired, 25M Cache, 416K Buf, 22G F= ree > Swap: 8192M Total, 8192M Free >=20 > PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMM= AND > 11 root 32 155 ki31 0K 512K CPU31 31 190.2H 1818.46% id= le > 0 root 268 -8 0 0K 4288K - 0 141:25 1261.33% ke= rnel > 4 root 4 -8 - 0K 80K CPU30 30 9:13 95.17% zfsk= ern > 13 root 3 -8 - 0K 48K - 4 5:37 42.97% geom= > 12 root 66 -84 - 0K 1056K WAIT 0 6:19 30.86% intr= > [...] > It seems that zfskern will top to 100%. This is an 32 core system, and > as you see scrub, at 600MB/sec is able to eat 16 cores (from 2x 2.2 GHz= If you hit "H", top will show threads separately, so you will see which threads exactly do the work (you might need to reduce your font so that all of them fit on the screen :) ). > Opteron 6274). There is high load on geom as well... but geom does go > over 100% CPU, so I suppose it scales. Actually, GEOM itself is a bottleneck with SSDs and not really scalable in its current version. If you hit H, you could see that e.g. the g_down thread is sometimes pinned to 100% CPU or something similar. If all GEOM threads in your case are individually below 100%, then you didn't hit the GEOM bottleneck yet. --------------enig5CC6457B180713D1070139C7 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlAyFPsACgkQ/QjVBj3/HSwYzgCfft3+Az6FgEYLk/qfIZVth9Xm EMkAoIIz2CqFG1AcaT7LeHs9wloTdJwj =p58/ -----END PGP SIGNATURE----- --------------enig5CC6457B180713D1070139C7--
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