Re: [2.4.17/18pre] VM and swap - it's really unusable

jogi
2002-01-12T15:12:00Z

On Sat, Jan 12, 2002 at 12:13:15PM +0100, Andrea Arcangeli wrote:
> On Fri, Jan 11, 2002 at 03:33:22PM -0500, Robert Love wrote:
> > On Fri, 2002-01-11 at 07:37, Alan Cox wrote:
> >
> > > Its more than a spinlock cleanup at that point. To do anything useful you have
> > > to tackle both priority inversion and some kind of at least semi-formal
> > > validation of the code itself. At the point it comes down to validating the
> > > code I'd much rather validate rtlinux than the entire kernel
> >
> > The preemptible kernel plus the spinlock cleanup could really take us
> > far. Having locked at a lot of the long-held locks in the kernel, I am
> > confident at least reasonable progress could be made.
> >
> > Beyond that, yah, we need a better locking construct. Priority
> > inversion could be solved with a priority-inheriting mutex, which we can
> > tackle if and when we want to go that route. Not now.
> >
> > I want to lay the groundwork for a better kernel. The preempt-kernel
> > patch gives real-world improvements, it provides a smoother user desktop
> > experience -- just look at the positive feedback. Most importantly,
> > however, it provides a framework for superior response with our standard
>
> I don't know how to tell you, positive feedback compared to mainline
> kernel is totally irrelevant, mainline has broken read/write/sendfile
> syscalls that can hang the machine etc... That was fixed ages ago in
> many ways, current way is very lightweight, if you can get positive
> feedback compared to -aa _that_ will matter.

Hello Andrea,

I did my usual compile testings (untar kernel archive, apply patches,
make -j<value> ...

Here are some results (Wall time + Percent cpu) for each of the consecutive five runs:

13-pre5aa1 18-pre2aa2 18-pre3 18-pre3s 18-pre3sp
j100: 6:59.79 78% 7:07.62 76% * 6:39.55 81% 6:24.79 83%
j100: 7:03.39 77% 8:10.04 66% * 8:07.13 66% 6:21.23 83%
j100: 6:40.40 81% 7:43.15 70% * 6:37.46 81% 6:03.68 87%
j100: 7:45.12 70% 7:11.59 75% * 7:14.46 74% 6:06.98 87%
j100: 6:56.71 79% 7:36.12 71% * 6:26.59 83% 6:11.30 86%

j75: 6:22.33 85% 6:42.50 81% 6:48.83 80% 6:01.61 89% 5:42.66 93%
j75: 6:41.47 81% 7:19.79 74% 6:49.43 79% 5:59.82 89% 6:00.83 88%
j75: 6:10.32 88% 6:44.98 80% 7:01.01 77% 6:02.99 88% 5:48.00 91%
j75: 6:28.55 84% 6:44.21 80% 9:33.78 57% 6:19.83 85% 5:49.07 91%
j75: 6:17.15 86% 6:46.58 80% 7:24.52 73% 6:23.50 84% 5:58.06 88%

* build incomplete (OOM killer killed several cc1 ... )

So far 2.4.13-pre5aa1 had been the king of the block in compile times.
But this has changed. Now the (by far) fastest kernel is 2.4.18-pre
+ Ingos scheduler patch (s) + preemptive patch (p). I did not test
preemptive patch alone so far since I don't know if the one I have
applies cleanly against -pre3 without Ingos patch. I used the
following patches:

s: sched-O1-2.4.17-H6.patch
p: preempt-kernel-rml-2.4.18-pre3-ingo-1.patch

I hope this info is useful to someone.

Kind regards,

Jogi

--

Well, yeah ... I suppose there's no point in getting greedy, is there?

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