Date: Thu, 16 Apr 2009 15:23:02 +0200 From: Peter Schuller <peter.schuller@infidyne.com> To: Artem Belevich <fbsdlist@src.cx> Cc: freebsd-current@freebsd.org, Ben Kelly <ben@wanderview.com> Subject: Re: [patch] zfs livelock and thread priorities Message-ID: <20090416132302.GA86096@hyperion.scode.org> In-Reply-To: <ed91d4a80904142135n429dea52o672abf51116fa707@mail.gmail.com> References: <DC9F2088-A0AF-467D-8574-F24A045ABD81@wanderview.com> <49C2CFF6.8070608@egr.msu.edu> <BDABA909-C2AE-4A55-869B-CA01BE778A82@wanderview.com> <ed91d4a80904131636u18c90474w7cdaa57bc7000e02@mail.gmail.com> <08D7DC2A-68BE-47B6-8D5D-5DE6B48F87E5@wanderview.com> <AC3C4C3F-40C6-4AF9-BAF3-2C4D1E444839@wanderview.com> <ed91d4a80904142135n429dea52o672abf51116fa707@mail.gmail.com>
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--rwEMma7ioTxnRzrJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > BTW, now that you're tinkering with ZFS threads and priorities, whould > you by any chance have any idea why zfs scrub is so painfully slow on > -current? > When I start scrub on my -stable box, it pretty much runs full speed > -- I can see disks under load all the time. > However on -current scrub seems to run in small bursts. Disks get busy > for a second or so and then things get quiet for about five seconds or > so and this pattern repeats over and over. This is intentional. The newer ZFS code has, if I remember correctly, something like "spend at most 1/5 of the time doing scrub for each underlying vdev". I could be wrong on the details and I don't have source refs off-hand, by I looked into this when I wanted to see if I could tweak this (while I definitely like it rate limited, I would have liked to up the threshold a bit). My conclusion at the time was that there was no way to tweak it other than recompiling the kernel. --=20 / Peter Schuller PGP userID: 0xE9758B7D or 'Peter Schuller <peter.schuller@infidyne.com>' Key retrieval: Send an E-Mail to getpgpkey@scode.org E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org --rwEMma7ioTxnRzrJ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (FreeBSD) iEYEARECAAYFAknnMTYACgkQDNor2+l1i336pACggYkwt6NFavYiTKKYZ3OH9EEK oK0AmwVcai3KXjdYK/C2Yaa3/aRC4W4h =K1CW -----END PGP SIGNATURE----- --rwEMma7ioTxnRzrJ--
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