On Thu, May 02, 2013 at 11:44:26AM -0700, Tejun Heo wrote: [..] > Also, if you're actually thinking about reimplementing blk-throttle, > please do consider the followings. > > * Currently, blk-throttle doesn't throttle the number of bios being > queued. Note that this breaks the basic back-pressure mechanism > where IO pressure is propagated back to the issuer by throttling the > issuing task. blk-throttle breaks that link and converts it to a > memory pressure. Agreed. Implementing something along the lines of per group nr_requests is needed. > > * It's almost inherently unscalable with highops devices. Given that > IO limiting doesn't require very fine granularity, I think doing > this per-cpu shouldn't be too hard. e.g. build a per-cpu token > distributing hierarchy with rebalancing across CPUs happening > periodically. Interesting. I thought for highops devices we will these multi queue patches from jens and there we can probably implement per queue tokens and rebalance tokens across queues periodically. > > In short, right now, the goal is getting the hierarchy support > acceptably working ASAP and yeap we wanna get the nested limits and at > least certain level of fairness, but let's please implement something > simple for now and strive for sophistification later because it's > holding back everyone else. I am fine with this. Having some hierarchical algorithm and not blocking full hierarchical support for cgroup is better than not having any hierachical support and wait for better implementation. Thanks Vivek _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
