Messages in this thread |  | | Date | Sun, 15 Sep 2002 11:55:21 -0700 | From | Andrew Morton <> | Subject | Re: 2.5.34-mm4 |
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Rik van Riel wrote: > > On Sun, 15 Sep 2002, M. Edward Borasky wrote: > > > Borasky's Corollary 1: If you *can* measure it and it *does* exist, the > > cheapest solution may still be to buy more memory, more disks or a > > faster processor. > > Current 2.5 is sluggish on systems with a fast CPU and 768 MB > of RAM, whereas current -ac runs the same workload smoothly > with 128 MB of RAM. >
I've been running 2.5 on my desktop at work (800MHz/256M UP) since 2.5.26 and on the machine at home (Dual 850MHz/768M) on-and-off (recent freizures sent that machine back to Marcelo; need to try again). I also ran 2.4.19-ac-something for a couple of weeks.
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.
- 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.
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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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