On Tue, Jun 22, 2010 at 05:34:59PM -0400, Jeff Moyer wrote: > Hi, > > Running iozone with the fsync flag, or fs_mark, the performance of CFQ is > far worse than that of deadline for enterprise class storage when dealing > with file sizes of 8MB or less. I used the following command line as a > representative test case: > > fs_mark -S 1 -D 10000 -N 100000 -d /mnt/test/fs_mark -s 65536 -t 1 -w 4096 -F > > When run using the deadline I/O scheduler, an average of the first 5 numbers > will give you 448.4 files / second. CFQ will yield only 106.7. With > this patch series applied (and the two patches I sent yesterday), CFQ now > achieves 462.5 files / second. > > This patch set is still an RFC. I'd like to make it perform better when > there is a competing sequential reader present. For now, I've addressed > the concerns voiced about the previous posting. What happened to the initial idea of just using the BIO_RW_META flag for log writes? In the end log writes are the most important writes you have in a journaled filesystem, and they should not be effect to any kind of queue idling logic or other interruption. Log I/O is usually very little (unless you use old XFS code with a worst-case directory manipulation workload), and very latency sensitive. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
