Messages in this thread | | | Date | Thu, 10 Oct 2002 13:40:49 -0400 (EDT) | From | Bill Davidsen <> | Subject | Re: [BENCHMARK] 2.5.40-mm2 with contest |
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On Tue, 8 Oct 2002, Con Kolivas wrote:
> > Problem is, users have said they don't want that. They say that they > > want to copy ISO images about all day and not swap. I think. > > But do they really want that or do they think they want that without knowing the > consequences of such a setting?
I have been able to tune bdflush in 2.4-aa kernels to be much more aggressive about moving data to disk under write pressure, and that has been a big plus in terms of both getting the write completed in less real time and fewer big pauses doing trivial things like uncovering a window. I see less swap used.
> > > It worries me. It means that we'll be really slow to react to sudden > > load swings, and it increases the complexity of the analysis and > > testing. And I really do want to give the user a single knob, > > which has understandable semantics and for which I can feasibly test > > all operating regions. > > > > I really, really, really, really don't want to get too fancy in there. > > Well I made it as simple as I possibly could. It seems to do what they want (not > swappy) but not at the expense of making the machine never swapping when it > really needs to - and the performance seems to be better all round in real > usage. I guess the only thing is it isn't a fixed number... unless we set a > maximum swappiness level or... but then it starts getting unnecessarily > complicated with questionable benefits.
I'm going to try this patch, but building a kernel on my standard test machine is painfully slow, so it will come after 41-ac2. It appears to address the balance issue dynamically.
> > I have changed this code a bit, and have added other things. Mainly > > over on the writer throttling side, which tends to be the place where > > the stress comes from in the first place. > > /me waits but is a little disappointed
I actually like the idea of writer throttling, I just wonder how it will work at the corner cases like only one big writer (mkisofs) or the alternative, lots of little writers.
-- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.
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