On Thu, Jun 25, 2015 at 05:38:56PM -0400, Tejun Heo wrote: > Currently, both cfq-iosched and blk-throttle keep track of > io_service_bytes and io_serviced stats. While keeping track of them > separately may be useful during development, it doesn't make much > sense otherwise. Also, blkcg stats are collected at different points > and ignoring blk_do_io_stat() which can lead to subtly different > results which are more confusing than helpful. > > This patch adds ->stat_bytes and ->stat_ios to blkg (blkcg_gq), > removes the counterparts from cfq-iosched and blk-throttle and let > them print from the common blkg counters. > > The outputs are still filtered by whether the policy has > blkg_policy_data on a given blkg, so cfq's output won't show up if it > has never been used for a given blkg. The only times when the outputs > would differ significantly are when policies are attached on the fly > or elevators are switched back and forth. Those are quite exceptional > operations and I don't think they warrant keeping separate counters. > Hi Tejun, I have some questions and concerns. - Previously throttling policy was calculating number of IOs in terms of number of bios while CFQ was calculating it in terms of number of requests. I think this will be a behavior change now? IIUC, now even throttling policy will report number of requests and number of bios. - Looks like completion and stat is now lined to request. I am wondering what will happen to bio based targets. One can put a throttling policy on any of the stacked dm devices. I suspect we will be broken there? - Can you please also update the blkio-controller.txt. Specifically blkio.throttle.io_serviced. Thanks Vivek -- 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
