Date: Wed, 26 Sep 2007 12:36:44 +0100 From: bruce@cran.org.uk To: current@freebsd.org Subject: Interrupt storm on ahc0 when drm module is loaded Message-ID: <20070926113643.GA21109@muon.bluestop.org>
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I've come some sort of conflict between the drm and ahc drivers: whenever drm is loaded I get an interrupt storm on ahc0. My system is: 7.0-CURRENT #0: Tue Sep 25 18:08:50 BST 2007 /usr/obj/usr/src/sys/GENERIC i386 I'm running Xorg 7.3 ahc0: <Adaptec 19160B Ultra160 SCSI adapter> port 0xdc00-0xdcff mem 0xd9200000-0xd9200fff irq 16 at device 9.0 on pci0 ahc0: [ITHREAD] da0 at ahc0 bus 0 target 6 lun 0 drm0: <Matrox G200 (AGP)> on vgapci0 info: [drm] AGP at 0xd0000000 64MB info: [drm] Initialized mga 3.2.2 20060319 info: [drm] Initialized card for AGP DMA drm0: [ITHREAD] vmstat -i: interrupt total rate irq1: atkbd0 4036 0 irq14: ata0 58 0 irq16: ahc0 15004943 2824 irq19: fxp0 40961 7 cpu0: timer 10624196 1999 cpu1: timer 10606936 1996 Total 36281130 6828 Over time the rate for ahc0 grows until I get the "Interrupt storm detected: throttling irq16" messages. I can trigger the problem by changing the default colour depth to 16 bits in my xorg.conf file: this enables the drm module to load and immediately the interrupt rate starts to climb. -- Bruce
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