Date: Tue, 13 Oct 2009 14:35:42 +0200 From: "Svein Skogen (listmail account)" <svein-listmail@stillbilde.net> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: Extreme console latency during disk IO (8.0-RC1, previous releases also affected according to others) Message-ID: <4AD4741E.3080108@stillbilde.net> In-Reply-To: <hb1qs0$qjd$1@ger.gmane.org> References: <E316139E-FFCF-432F-8DCE-62B120C38E55@exscape.org> <CC16B639-7A75-4016-A8A8-5C59E9CD5E95@exscape.org> <hb1qs0$qjd$1@ger.gmane.org>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Ivan Voras wrote: > Thomas Backman wrote: >> I'm copying this over from the freebsd-performance list, as I'm >> looking for a few more opinions - not on the problems *I* am having, >> but rather to check whether the problem is universal or not, and if >> not, find a possible common factor. >> In other words: I want to hear about your experiences, *good or bad*! >> >> Here's the original thread (not from the beginning, though): >> http://lists.freebsd.org/pipermail/freebsd-performance/2009-October/00= 3843.html >> >> >> Long story short, my version: when the disk is stressed hard enough, >> console IO becomes COMPLETELY unbearable. 10+ seconds to switch >> between windows in screen(1), running (or even typing) simple >> commands, etc. This happens both via SSH and the serial console. >=20 > Hmm, this looks familiar - I've noticed it before on the physical (VGA) > console and I notice it all the time under VMWare. It sort of looks lik= e > disk IO really blocks network IO in this case - I use the VMs over ssh. I've seen some similar behaviour here with my zfs/istgt backend. I "resolved" the issue by reducing the arc_max so that each disk-io cycle would be "short enough" not to cause the istgt to generate timeouts towards my two vmware hosts. The io-backend for the box is a megaraid 8308 (mfi) card with 8 disks on it. This box is running RELENG_7 now (I tried running it with RELENG_8 but it had a nasty tendency of simply locking up, dragging down both my ESXi hosts with it). //Svein - -- - --------+-------------------+------------------------------- /"\ |Svein Skogen | svein@d80.iso100.no \ / |Solberg =C3=98stli 9 | PGP Key: 0xE5E76831 X |2020 Skedsmokorset | svein@jernhuset.no / \ |Norway | PGP Key: 0xCE96CE13 | | svein@stillbilde.net ascii | | PGP Key: 0x58CD33B6 ribbon |System Admin | svein-listmail@stillbilde.net Campaign|stillbilde.net | PGP Key: 0x22D494A4 +-------------------+------------------------------- |msn messenger: | Mobile Phone: +47 907 03 575 |svein@jernhuset.no | RIPE handle: SS16503-RIPE - --------+-------------------+------------------------------- If you really are in a hurry, mail me at svein-mobile@stillbilde.net This mailbox goes directly to my cellphone and is checked even when I'm not in front of my computer. - ------------------------------------------------------------ Picture Gallery: https://gallery.stillbilde.net/v/svein/ - ------------------------------------------------------------ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkrUdB4ACgkQODUnwSLUlKQjtwCcDWA7BqDdwQ6w8zo0shNJDpJW shkAoKK1hN5QVrmg59J4lGV3V45ooiPj =3DnUay -----END PGP SIGNATURE-----
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