Re: BFS vs. mainline scheduler benchmarks and measurements

From: Jens Axboe
Date: Mon Sep 07 2009 - 14:46:45 EST

On Mon, Sep 07 2009, Avi Kivity wrote:
> On 09/07/2009 12:49 PM, Jens Axboe wrote:
>> I ran a simple test as well, since I was curious to see how it performed
>> wrt interactiveness. One of my pet peeves with the current scheduler is
>> that I have to nice compile jobs, or my X experience is just awful while
>> the compile is running.
> I think the problem is that CFS is optimizing for the wrong thing. It's
> trying to be fair to tasks, but these are meaningless building blocks of
> jobs, which is what the user sees and measures. Your make -j128
> dominates your interactive task by two orders of magnitude. If the
> scheduler attempts to bridge this gap using heuristics, it will fail
> badly when it misdetects since it will starve the really important
> 100-thread job for a task that was misdetected as interactive.

Agree, I was actually looking into doing joint latency for X number of
tasks for the test app. I'll try and do that and see if we can detect
something from that.

Jens Axboe

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