On Mon, May 11, 2009 at 08:23:09PM +0900, Ryo Tsuruta wrote: > Hi Vivek, > > From: Vivek Goyal <vgoyal@xxxxxxxxxx> > Subject: Re: IO scheduler based IO Controller V2 > Date: Wed, 6 May 2009 21:25:59 -0400 > > > On Thu, May 07, 2009 at 09:18:58AM +0900, 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. > > > > > > > Same is possible with IO scheduler based controller. If you don't want > > cgroup stuff, don't create those. By default everything will be in root > > group and you will get the old behavior. > > > > If you want io controller stuff, just create the cgroup, assign weight > > and move task there. So what more choices do you want which are missing > > here? > > What I mean to say is that device-mapper drivers can be completely > removed from the kernel if not used. > > I know that dm-ioband has some issues which can be addressed by your > IO controller, but I'm not sure your controller works well. So I would > like to see some benchmark results of your IO controller. > Fair enough. IO scheduler based IO controller is still work in progress and we have started to get some basic things right. I think after 3-4 iterations of patches, patches will be stable enough and working enough that I should be able to give some benchmark numbers also. Currently I am posting the intermediate snapshot of my tree to lkml to get the design feedback so that if there are fundamental design issues, we can sort these out. Thanks Vivek -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
