Hello, Vivek. On Thu, May 02, 2013 at 03:31:39PM -0400, Vivek Goyal wrote: > I think my example was little flawed previously. I think you are right. > Penalty is not probably as bad as I have been thinking. > > So if both parent and child have limit of 1MB/s and application is doing > IO (say at 2MB/sec), in long term it should still see 1MB/s rate. > > T1 T2 T3 T4 T5 T6 > Parent group: B1 B2 B3 B4 B5 > Child group: B1 B2 B3 B4 B5 B6 > > Above B1 to B6 are bios of 1MB size. T1 to T6 are 1 second time interval. > B1 waits for T1 interval in child group and then for T2 interval in > parent group and then gets dispatched. But a pipe line has formed in > child group and B2 is waiting in child group in T2 slice. So penalty > is not double. > > So each group migration will add one extra wait period. In above case > 5 bios dispatched in 6 seconds. Longer the sampling interval, delay > remains the constant to one time interval and % penalty goes down. Yeah, I think that's what *should* be happening but not what I'm seeing. I'm seeing ~15% penalty. It works fine if there are more than one active children but with a single child configured at the same limit, it doesn't work as expected. I'm a bit lost where the difference is coming from. Hmmm... also in the above example, we really should be doing the following. T1 T2 T3 T4 T5 T6 Parent group: B1 B2 B3 B4 B5 B6 Child group: B1 B2 B3 B4 B5 B6 I mean, if there's no other IO going on, there's no point in delaying the first IO. ie. the slice should be considered as started before so that B1 can be issued immediately, right? Thanks. -- tejun _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
