Re: ~500 megs cached yet 2.6.5 goes into swap hell

Tim Connors
2004-04-30T03:20:29Z

Adam Kropelin <akropel1@rochester.rr.com> said on Thu, 29 Apr 2004 14:14:13 -0400:
> On Wed, Apr 28, 2004 at 09:47:45PM -0400, Rik van Riel wrote:
> > On Wed, 28 Apr 2004, Andrew Morton wrote:
> >
> > > OK, so it takes four seconds to swap mozilla back in, and you noticed it.
> > >
> > > Did you notice that those three kernel builds you just did ran in twenty
> > > seconds less time because they had more cache available? Nope.
> >
> > That's exactly why desktops should be optimised to give
> > the best performance where the user notices it most...
...
> The 'swappiness' tunable may well give enough control over the situation
> to suit all sorts of users. If nothing else, this thread has raised
> awareness that such a tunable exists and can be played with to influence
> the kernel's decision-making. Distros, too, should give consideration to
> appropriate default settings to serve their intended users.

Actually, I decided to investigate how 2.4 compares (we're still stuck
on 2.4)

According to this:
http://www.uwsg.iu.edu/hypermail/linux/kernel/0210.1/0011.html

2.6 with swapiness of 0% is same as 2.4.19 - I assume 2.4.19's VM is
the same as 2.4.26 (given feature freeze).

I have always been completely unimpressed with the 2.4 VM - before and
after the big change in ~2.4.10. It has *always* preferred to use
cache in preference to a recently used application.

So will this still apply to 2.6 with swapiness of 0%?

I might try to get my sysadmin to put on 2.6, becuase 2.4 is quite
unusable for some of the work I do (if I need mozilla at the same time
as my visualisation software, which allocates a good 3/4 of RAM, after
reading a file that is about that size, leaving still enough for
mozilla and X combined, mozilla and parts of X still get swapped out -
and the cahce is wasted, since I only ever read the file once, and it
is written on another host)

--
TimC -- http://astronomy.swin.edu.au/staff/tconnors/
"32-bit patch for a 16-bit GUI shell running on top of an
8-bit operating system written for a 4-bit processor by a
2-bit company who cannot stand 1 bit of competition."