On Fri, Oct 02 2009, Ray Lee wrote: > On Fri, Oct 2, 2009 at 7:56 AM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: > > In some cases I wish we had a server vs desktop switch, since it would > > decisions on this easier. I know you say that servers care about > > latency, but not at all to the extent that desktops do. Most desktop > > users would gladly give away the top of the performance for latency, > > that's not true of most server users. Depends on what the server does, > > of course. > > If most of the I/O on a system exhibits seeky tendencies, couldn't the > schedulers notice that and use that as the hint for what to optimize? > > I mean, there's no switch better than the actual I/O behavior itself. Heuristics like that have a tendency to fail. What's the cut-off point? Additionally, heuristics based on past process/system behaviour also has a tendency to be suboptimal, since things aren't static. We already look at seekiness of individual processes or groups. IIRC, as-iosched also keeps a per-queue tracking. -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
