Hi folks, I've started playing with the FLEX_BG feature (for now packing of block group metadata closer together) and started doing some preliminary benchmarking to see if the feature is worth pursuing. I chose an FFSB profile that does single threaded small creates and writes and then does an fsync. This is something I ran for a customer a while ago in which ext3 performed poorly. Here are some of the results (in transactions/sec@%CPU util) on a single 143GB@10K rpm disk. ext4 1680.54@xxx% ext4(flex_bg) 2105.56@xxx% 20% improvement ext4(data=writeback) 1374.50@xxx% <- hum... ext4(flex_bg data=writeback) 2323.12@xxx% 28% over best ext4 ext3 1025.84@xxx% ext3(data=writeback) 1136.85@xxx% ext2 1152.59@xxx% xfs 1968.84@xxx% jfs 1424.05@xxx% The results are from packing the metadata of 64 block groups closer together at fsck time. Still need to clean up the e2fsprog patches, but I hope to submit them to the list later this week for others to try. It seems like fsck doesn't quite like the new location of the metadata and I'm not sure how big of an effort it will be to fix it. I mentioned this since one of the assumptions of implementing FLEX_BG was the reduce time in fsck and it could be a while before I'm able to test this. -JRS - 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
