Ming-Lei it sounds like a really good explanation. But when I test it, I don't see any real difference on USB memory stick before and after. Maybe my test is broken somehow?
8GB no-name USB stick Before the patch --> root@linaro:~# dd if=/dev/urandom of=/media/dump bs=40960 count=1000 1000+0 records in 1000+0 records out 40960000 bytes (41 MB) copied, 21.9735 s, 1.9 MB/s root@linaro:~# dd if=/dev/urandom of=/media/dump bs=40960 count=1000 1000+0 records in 1000+0 records out 40960000 bytes (41 MB) copied, 21.3798 s, 1.9 MB/s root@linaro:~# dd if=/dev/urandom of=/media/dump bs=40960 count=1000 1000+0 records in 1000+0 records out 40960000 bytes (41 MB) copied, 21.3694 s, 1.9 MB/s After the patch --> root@linaro:~# mount /dev/sda1 /media/ root@linaro:~# dd if=/dev/urandom of=/media/dump bs=40960 count=1000 1000+0 records in 1000+0 records out 40960000 bytes (41 MB) copied, 21.6143 s, 1.9 MB/s root@linaro:~# dd if=/dev/urandom of=/media/dump bs=40960 count=1000 1000+0 records in 1000+0 records out 40960000 bytes (41 MB) copied, 21.6175 s, 1.9 MB/s root@linaro:~# dd if=/dev/urandom of=/media/dump bs=40960 count=1000 1000+0 records in 1000+0 records out 40960000 bytes (41 MB) copied, 21.5983 s, 1.9 MB/s I like the idea the delay is coming from L2 cache not being evicted until something else forces it a lot though. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/709245 Title: ARM SMP scheduler performance bug To manage notifications about this bug go to: https://bugs.launchpad.net/linaro-ubuntu/+bug/709245/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
