Hi Rik, Rik van Riel <riel@xxxxxxxxxx> wrote: > Ryo Tsuruta wrote: > > > However, if you want to get fairness in a case like this, a new > > bandwidth control policy which controls accurately according to > > assigned weights can be added to dm-ioband. > > Are you saying that dm-ioband is purposely unfair, > until a certain load level is reached? Not unfair, dm-ioband(weight policy) is intentionally designed to use bandwidth efficiently, weight policy tries to give spare bandwidth of inactive groups to active groups. > > We regarded reducing throughput loss rather than reducing duration > > as the design of dm-ioband. Of course, it is possible to make a new > > policy which reduces duration. > > ... while also reducing overall system throughput > by design? I think it reduces system throughput compared to the current implementation, because it causes more overhead to do fine grained control. > Why are you even bothering to submit this to the > linux-kernel mailing list, when there is a codebase > available that has no throughput or fairness regressions? > (Vivek's io scheduler based io controler) I think there are some advantages to dm-ioband. That's why I post dm-ioband to the mailing list. - dm-ioband supports not only proportional weight policy but also rate limiting policy. Besides, new policies can be added to dm-ioband if a user wants to control bandwidth by his or her own policy. - The dm-ioband driver can be replaced without stopping the system by using device-mapper's facility. It's easy to maintain. - dm-ioband can use without cgroup. (I remember Vivek said it's not an advantage.) Thanks, Ryo Tsuruta -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
