This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed- saucy' to 'verification-done-saucy'.
If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: verification-needed-saucy -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1242812 Title: ext4 random block I/O write performance regression with 3.11 Saucy Kernel Status in “linux” package in Ubuntu: Fix Committed Bug description: Commit e7ea81db5(ext4: restructure writeback path) introduced a performance regression with random writes. Using tools such as bonnie++, writes with dd or even stress testing with tools such as 'stress' one can observe a 10%-20% performance regression. SRU Justification: Commit e7ea81db5(ext4: restructure writeback path) introduced a performance regression with random writes. Using tools such as bonnie++, writes with dd or even stress testing with tools such as 'stress' one can observe a 10%-20% performance regression. Impact: Write performance is diminished causing a noticeable regression compared to previous released kernels. Fix: Two patches are required: a) upstream fix 9c12a83 which fixes the overly aggressive writing back of pages which ultimulately resulted in more seeking and less performance. b) commit aeac589a7 from the dev branch of kernel/git/tytso/ext4.git which ensures no more pages than nr_to_write can be added to the extent for mapping. Testcase: Using stress-ng on a 2 CPU machine run: stress-ng --hdd 2 --hdd-ops 200000 (see: git://kernel.ubuntu.com/cking/stress-ng.git) With the fix, this consistently runs ~10-20% faster than the non-fixed kernel. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1242812/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
