* Mike Galbraith <efault@xxxxxx> wrote: > On Fri, 2009-10-02 at 11:24 +0200, Ingo Molnar wrote: > > * Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: > > > > > It's not hard to make the latency good, the hard bit is making sure we > > > also perform well for all other scenarios. > > > > Looking at the numbers from Mike: > > > > | dd competing against perf stat -- konsole -e exec timings, 5 back to > > | back runs > > | Avg > > | before 9.15 14.51 9.39 15.06 9.90 11.6 > > | after [+patch] 1.76 1.54 1.93 1.88 1.56 1.7 > > > > _PLEASE_ make read latencies this good - the numbers are _vastly_ > > better. We'll worry about the 'other' things _after_ we've reached good > > latencies. > > > > I thought this principle was a well established basic rule of Linux > > IO scheduling. Why do we have to have a 'latency vs. bandwidth' > > discussion again and again? I thought latency won hands down. > > Just a note: In the testing I've done so far, we're better off today > than ever, [...] Definitely so, and a couple of months ago i've sung praises of that progress on the IO/fs latencies front: http://lkml.org/lkml/2009/4/9/461 ... but we are greedy bastards and dont define excellence by how far down we have come from but by how high we can still climb ;-) Ingo -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
