On Thu 11-10-12 13:23:32, Alex Bligh wrote: > We have noticed significant I/O scheduling issues on both the CFQ and the > deadline scheduler where a non-root user can starve any other process of > any I/O for minutes at a time. The problem is more serious using CFQ but is > still an effective local DoS vector using Deadline. > > A simple way to generate the problem is: > > dd if=/dev/zero of=- bs=1M count=50000 | dd if=- of=myfile bs=1M count=50000 > [...] > > Full info, including logs and scripts can be found at: > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1064521
You seem to have 8G of RAM and dirty_ratio=20 resp. dirty_background_ratio=10 which means that 1.5G worth of dirty data until writer gets throttled which is a lot. Background writeback starts at 800M which is probably not sufficient as well. Have you tried to set dirty_bytes at a reasonable value (wrt. to your storage)? -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
