Messages in this thread |  | | Date | Mon, 16 Sep 2002 14:48:35 -0400 (EDT) | From | Bill Davidsen <> | Subject | Re: 2.5.34-mm4 |
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On Sun, 15 Sep 2002, Andrew Morton wrote:
> Impressions are: > > - 2.5 swaps a lot in response to heavy pagecache activity. > > SEGQ didn't change that, actually. And this is correct, > as-designed behaviour. We'll need some "don't be irritating" > knob to prevent this. Or speculative pagein when the load > has subsided, which would be a fair-sized project.
It would be nice to have a knob in /proc/sys which could be tuned for response or throughput, Preferably not a boolean;-) I suspect that we would have lack of agreement on what that would do, but it sure would be nice!
> - In both -ac and 2.5 the scheduler is prone to starving interactive > applications (netscape 4, gkrellm, command-line gdb, others) when > there is a compilation happening. > > This is very, very noticeable; and it afects applications which > do not use sched_yield(). Ingo has put some extra stuff in since > then and I need to retest. > > - In -ac, there are noticeable stalls during heavy writeout. This > may be an ext3 thing, but I can't think of any IO scheduling > differences in -ac ext3. I'd be guessing that it is due to > bdflush/kupdate lumpiness.
I have the feeling that 2.5 is less good about noting that a file is open for write only and no seeks have been done. I haven't measured it, but it would seem that writes to such a file would be better on the disk and not taking buffers, since they're probably not going to be read.
This is just based on running mkisofs on 2.4.19 and 2.5.34, a watching "no disk activity" followed by a heavy burst. I haven't made any careful measurement, so take this as you will, but I agree that heavy write bogs the system. Clearly with big memory I can/do get the whole ~700MB in memory if writes don't start quickly.
Yes, that could be tuning, I know that.
> Overall I find Marcelo kernels to be the most comfortable, followed > by 2.5. Alan's kernels I find to be the least comfortable in a > "developer's desktop" situation.
On small memory machines I don't see as much to choose, and the -ck series has been very nice to me. I don't run 2.5 on any but test machines, and both are big memory (1+GB) machines.
-- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.
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