Hi Vivek, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > > > > > - Somebody also gave an example where there is a memory hogging process and > > > > > > possibly pushes out some processes to swap. It does not sound fair to > > > > > > charge those proccess for that swap writeout. These processes never > > > > > > requested swap IO. > > > > > > > > I think that swap writeouts should be charged to the memory hogging > > > > process, because the process consumes more resources and it should get > > > > a penalty. > > > > > > > > > > A process requesting memory gets IO penalty? IMHO, swapping is a kernel > > > mechanism and kernel's way of providing extended RAM. If we want to solve > > > the issue of memory hogging by a process then right way to solve is to use > > > memory controller and not by charging the process for IO activity. > > > Instead, proabably a more suitable way is to charge swap activity to root > > > group (where by default all the kernel related activity goes). > > > > No. In the current blkio-cgroup, a process which uses a large amount > > of memory gets penalty, not a memory requester. > > > > At ioband level you just get to see bio and page. How do you decide wheter > this bio is being issued by a process which is a memory hog? > > In fact requester of memory could be anybody. It could be memory hog or a > different process. So are you saying that you got a mechanism where you > can detect that a process is memory hog and charge swap activity to it. > IOW, if there are two processes A and B and assume A is the memory hog and > then B requests for memory which triggers lot of swap IO, then you can > charge all that IO to memory hog A? When an annoymou page is allocated, blkio-cgroup sets an ID to the page. And then when the page is going to swap out, dm-ioband can know who the owner of the page is by retrieving ID from the page. In the above case, since the pages of the process A are swapped-out, dm-ioband charges swap IO to the process A. > Can you please point me to the relevant code in dm-ioband? > > IMHO, to keep things simple, all swapping activity should be charged to > root group and be considered as kernel activity and user space not be > charged for that. Thanks, Ryo Tsuruta -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
