https://bugzilla.kernel.org/show_bug.cgi?id=199727 --- Comment #3 from Roland Kletzing (devzero@xxxxxx) --- i had a look at kvm process with strace. with virtual disk caching option set to "Default (no cache)", kvm is doing IO submission via io_submit() instead of pwritev(), and apparently that can be a long blocking call. i see whenever the VM getting hickup and pingtime goes through the roof, there is long blocking io_submit() operation in progress looks like a "design issue" to me and "Default (no cache)" thus being a bad default setting. see: https://lwn.net/Articles/508064/ and https://stackoverflow.com/questions/34572559/asynchronous-io-io-submit-latency-in-ubuntu-linux -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
