Hello, I'm observing blkcg throttle limits to not apply on writes which go through the page cache. E.g. I have a container whose write iops limits are set to 300 I then run a fio job with direct=0 (the default) and can see that writes/s (via iostat) are around 6-7k. Tracing confirmed thae AIO that fio is submitting is being handled by a kworker thread, which is in the root cgroup and as such has no lio limits. Direct writes/reads work as expected and are throttled. After Paolo Valente's patch (https://patchwork.kernel.org/patch/9249247/) I was left with the impression that bios submitted would just carry the information of the submitted throughout the storage stack. Apparently this is not the case. I also went through an old thread I started on dm-devel dealing with this exact problem (even before Paolo's patch), where Vivel Goyal hinted at this particular problem : https://www.redhat.com/archives/dm-devel/2016-March/msg00012.html So Tejun, my question is what is the problem for the blkcg information to be transferred alongside the bio (which I believed to be happening with the blkcg_association calls) so that even buffered writes are throttled via the cgroup policies? Or are the numbers I'm seeing in iostat actually the writes to the page-cache and not the underlying block device? Regards, Nikolay -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
