KAMEZAWA Hiroyuki wrote:> On Tue, 05 Aug 2008 09:20:18 -0700> Dave Hansen <dave@xxxxxxxxxxxxxxxxxx> wrote:> >> On Tue, 2008-08-05 at 11:28 +0200, Andrea Righi wrote:>>>> Buffered write I/O is also related with cache system.>>>> We must consider this problem as I/O control.>>> Agree. At least, maybe we should consider if an IO controller could be>>> a valid solution also for these problems.>> Isn't this one of the core points that we keep going back and forth>> over? It seems like people are arguing in circles over this:>>>> Do we:>> 1. control potential memory usage by throttling I/O>> or>> 2. Throttle I/O when memory is full>>>> I might lean toward (1) if we didn't already have a memory controller.>> But, we have one, and it works. Also, we *already* do (2) in the>> kernel, so it would seem to graft well onto existing mechanisms that we>> have.>>>> I/O controllers should not worry about memory. > I agree here ;)> >> They're going to have a hard enough time getting the I/O part right. :)>>> memcg have more problems now ;( > > Only a difficult thing to limit dirty-ratio in memcg is how-to-count dirty> pages. If I/O controller's hook helps, it's good.> > My small concern is "What happens if we throttole I/O bandwidth too small> under some memcg." In such cgroup, we may see more OOMs because I/O will> not finish in time.> A system admin have to find some way to avoid this.> > But please do I/O control first. Dirty-page control is related but different> layer's problem, I think. Yes, please solve the I/O control problem first. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL _______________________________________________Containers mailing listContainers@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx://lists.linux-foundation.org/mailman/listinfo/containers
