Begin forwarded message: Date: Wed, 12 Jul 2006 09:46:52 -0500 From: Dave Lloyd <dlloyd@xxxxxxxxx> To: linux-kernel@xxxxxxxxxxxxxxx, Berkley Shands <bshands@xxxxxxxxx> Subject: MegaRaid 8408E goes out to lunch with nr_requests > 8 This happens both on 2.6.17 and 2.6.18rc1 using the megaraid, mptsas and mptscsih drivers supplied with the kernel. While writing data to raid0 devs on a LSI MegaRaid 8408E controller, the devices will hang after somewhere between 4-7gb of data written. If I dial the nr_requests back from the default down to 8, the hang will not occur. The hang does occur at 16. I haven't tested values between the two, but I'm not too optimistic. From what I can see, it looks like 8 should be a magic number to make the queue look congested more often than not. Here are the messages I get when the devices go out to lunch: Jul 11 14:13:34 systemname kernel: sd 4:2:0:0: megasas: RESET -40213 cmd=2a Jul 11 14:13:34 systemname kernel: megasas: [ 0]waiting for 256 commands to complete Jul 11 14:13:39 systemname kernel: megasas: [ 5]waiting for 256 commands to complete Jul 11 14:13:44 systemname kernel: megasas: [10]waiting for 256 commands to complete Jul 11 14:13:49 systemname kernel: megasas: [15]waiting for 256 commands to complete [...] Jul 11 14:16:35 systemname kernel: megasas: [175]waiting for 256 commands to complete Jul 11 14:16:35 systemname kernel: megasas: failed to do reset Jul 11 14:16:35 systemname kernel: sd 4:2:1:0: megasas: RESET -40216 cmd=2a Jul 11 14:16:35 systemname kernel: megasas: cannot recover from previous reset failures Jul 11 14:16:35 systemname kernel: sd 4:2:0:0: megasas: RESET -40213 cmd=2a Jul 11 14:16:35 systemname kernel: megasas: cannot recover from previous reset failures Jul 11 14:16:35 systemname kernel: sd 4:2:0:0: megasas: RESET -40213 cmd=2a Jul 11 14:16:35 systemname kernel: megasas: cannot recover from previous reset failures Jul 11 14:16:35 systemname kernel: sd 4:2:0:0: scsi: Device offlined - not ready after error recovery Jul 11 14:16:36 systemname last message repeated 13 times Interestingly, the machine will hang on shutdown and requires a hard reset to reboot. Bummer! My next step is to try and reproduce and dig into this some in KDB. Has anyone else seen this and/or does anyone have some suggestions for further debugging info? -- Dave Lloyd Test Engineer, Exegy, Inc. 314.450.5342 dlloyd@xxxxxxxxx -- Dave Lloyd Test Engineer, Exegy, Inc. 314.450.5342 dlloyd@xxxxxxxxx - : send the line "unsubscribe linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
