Hi All, I use sg/libata and ata pass through for read/writes. Linux 2.6.18-rc2 and libata version 2.00 are loaded on ARM XScale board. Under heavy cpu load (e.g. when blocks per transfer/sector count is set to 1), I've observed that the test application can suck cpu away for long time (more than 20 seconds) and other processes including high priority shell can not get the time slice to run. What's interesting is that if the application is under heavy IO load (e.g. when blocks per transfer/sector count is set to 256), the problem goes away. I also tested with open source code sg_utils and got the same result, so this is not a problem specific to my user-space application. Since user preemption is checked when the kernel is about to return to user-space from a system call, process scheduler should be invoked after each system call. Something seems to be broken here. I found a similar issue below: http://marc.info/?l=linux-arm-kernel&m=103121214521819&w=2 But that turns out to be an issue with MTD/JFFS2 drivers, which are not used in my system. Has anyone experienced similar issues with sg/libata? Any information would be greatly appreciated. Thanks, Fajun - To unsubscribe from this list: 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
