Just tested again on new Ubuntu 18.04 with kernel 4.15. The direct synchronous small 4K write performance is still slower than kernel 4.4 on Ubuntu 16.04.
Are kernel 4.13 and 4.15 having write performance issue on qemu 2.11.x? ## # ubuntu bionic kernel 4.15. the direct synchronous write performance is still 93% slower than kernel 4.4 on ubuntu xenial. ## root@localhost:~# dd if=/dev/zero of=/tmp/test bs=4K count=256 oflag=direct,sync status=progress; rm /tmp/test 1048576 bytes (1.0 MB, 1.0 MiB) copied, 3.504 s, 299 kB/s root@localhost:~# dd if=/dev/zero of=/tmp/test bs=4M count=256 oflag=direct,sync status=progress; rm /tmp/test 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 3.00597 s, 357 MB/s root@localhost:~# uname -a Linux localhost 4.15.0-20-generic #21-Ubuntu SMP Tue Apr 24 06:16:15 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1758621 Title: Ubuntu Xenial HWE Kernel 4.13 Direct Sync Write Performance Regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe/+bug/1758621/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
