Hello, Paolo. On Fri, Sep 06, 2019 at 11:07:17AM +0200, Paolo Valente wrote: > email. As for the filesystem, I'm interested in ext4, because it is > the most widely used file system, and, with some workloads, it makes Ext4 can't do writeback control as it currently stands. It creates hard ordering across data writes from different cgroups. No matter what mechanism you use for IO control, it is broken. I'm sure it's fixable but does need some work. That said, read-only tests like you're doing should work fine on ext4 too but the last time I tested io control on ext4 is more than a year ago so something might have changed in the meantime. Just to rule out this isn't what you're hitting. Can you please run your test on btrfs with the following patchset applied? http://lkml.kernel.org/r/20190710192818.1069475-1-tj@xxxxxxxxxx And as I wrote in the previous reply, I did run your benchmark on one of the test machines and it did work fine. Thanks. -- tejun
