Date: Mon, 09 Jul 2007 13:15:24 +0100 From: Thomas Hurst <tom@hur.st> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/114438: Anomalous performance with multiple arrays and amr(4) Message-ID: <E1I7s9E-0009fT-7n@voi.aagh.net> Resent-Message-ID: <200707091240.l69Ce4RN057558@freefall.freebsd.org>
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>Number: 114438 >Category: kern >Synopsis: Anomalous performance with multiple arrays and amr(4) >Confidential: no >Severity: non-critical >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Mon Jul 09 12:40:04 GMT 2007 >Closed-Date: >Last-Modified: >Originator: Thomas Hurst >Release: FreeBSD 6.2-STABLE amd64 >Organization: >Environment: System: FreeBSD voi.nightsdawn.sf 6.2-STABLE FreeBSD 6.2-STABLE #0: Wed Jul 4 13:46:52 BST 2007 root@voi.nightsdawn.sf:/usr/obj/usr/src/sys/VOI amd64 8GB dual dual core Opteron amr0: <LSILogic LSI MegaRAID SATA300-8X PCI-X> Firmware 814B, BIOS H431, 128MB RAM amrd0: 190713MB (390580224 sectors) RAID 1 (optimal) amrd1: 381485MB (781281280 sectors) RAID 1 (optimal) amrd2: 381485MB (781281280 sectors) RAID 1 (optimal) >Description: Performing heavy random IO on any one array causes other arrays to stall intermitently. For example: find /usr >/dev/null & # on amrd0 dd if=/dev/amrd1 of=/dev/null bs=128k gstat shows amrd0 doing a few hundred ops/sec and up to a few MB/s amrd1 runs at the expected 65MB/s for ~10 seconds, then stops for 2-3, before returning to 65MB/s. This behavior is seen with lighter serial transfers; I normally notice it while streaming movies or music at 100-1000k/s and daily run kicks in, causing annoying pauses in playback without the use of fairly large buffers. Multiple serial transfers on different arrays do not have the same problem; I can dd from or to all arrays without unexplained pauses. ata(4) disks on the system are unaffected. >How-To-Repeat: See above. >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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