Messages in this thread | | | Date | Fri, 08 May 2009 10:24:50 -0400 | From | Rik van Riel <> | Subject | Re: IO scheduler based IO Controller V2 |
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Ryo Tsuruta wrote: > Hi Vivek, > >> Ryo, dm-ioband breaks the notion of classes and priority of CFQ because >> of FIFO dispatch of buffered bios. Apart from that it tries to provide >> fairness in terms of actual IO done and that would mean a seeky workload >> will can use disk for much longer to get equivalent IO done and slow down >> other applications. Implementing IO controller at IO scheduler level gives >> us tigher control. Will it not meet your requirements? If you got specific >> concerns with IO scheduler based contol patches, please highlight these and >> we will see how these can be addressed. > > I'd like to avoid making complicated existing IO schedulers and other > kernel codes and to give a choice to users whether or not to use it. > I know that you chose an approach that using compile time options to > get the same behavior as old system, but device-mapper drivers can be > added, removed and replaced while system is running.
I do not believe that every use of cgroups will end up with a separate logical volume for each group.
In fact, if you look at group-per-UID usage, which could be quite common on shared web servers and shell servers, I would expect all the groups to share the same filesystem.
I do not believe dm-ioband would be useful in that configuration, while the IO scheduler based IO controller will just work.
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