Messages in this thread | | | Date | Thu, 30 Mar 2006 22:31:32 -0500 | From | Bill Davidsen <> | Subject | Re: RSS Limit implementation issue |
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Peter Chubb wrote:
>>>>>>"Bill" == Bill Davidsen <davidsen@tmr.com> writes: >>>>>> >>>>>> > >Bill> Ram Gupta wrote: > >Bill> If you want to make rss a hard limit the result should be >Bill> swapping, not failure to run. I'm not sure the limit in that >Bill> form is a good idea, and before someone reminds me, I do >Bill> remember liking it better a few years ago. > >Bill> If you can come up with a better way to adjust rss to get better >Bill> overall greater throughput while being fair to all processes, go >Bill> to it. But in general these things are a tradeoff, like >Bill> swappiness, you tune until the volume of complaints reaches a >Bill> minimum. > >What I did in one experiment was to: > 1. delay swapin requests if the process was over its rsslimit, > until it fell below, and > 2. Poke the swapper to try to swap out the current process's > pages in that case. > >The problem with the approach is that it behaved poorly under memory >pressure. If a process's optimum working set was larger than its RSS >limit, then either it was delayed to the point of glaciality, or it >could saturate the swap device (and so disturb other processes's >operation). > > > I'm paying close attention, but that's kind of the problem people have, memory pressure gets high and the processes don't run. I thought of "swap out two to swap in one" as a way to dribble the rss down, but I doubt it's a magic solution. Swap kills, so does not swap and no memory. Obvious solution is to make the rss limit hard and keep it small, I don't think that's the answer.
-- bill davidsen <davidsen@tmr.com> CTO TMR Associates, Inc Doing interesting things with small computers since 1979
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