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

From: Nick Piggin
Date: Fri Apr 30 2004 - 01:36:23 EST


Tim Connors wrote:
Horst von Brand <vonbrand@xxxxxxxxxxxx> said on Thu, 29 Apr 2004 16:01:11 -0400:

Nick Piggin <nickpiggin@xxxxxxxxxxxx> said:

[...]


I don't know. What if you have some huge application that only
runs once per day for 10 minutes? Do you want it to be consuming
100MB of your memory for the other 23 hours and 50 minutes for
no good reason?

How on earth is the kernel supposed to know that for this one particular
job you don't care if it takes 3 hours instead of 10 minutes, just because
you don't want to spare enough preciousss RAM?


Note that we are not talking about having insufficient memory. In my
case (2.4 kernel - ie, 2.6 with swapiness 0%) there is more than
enough memory to contain all my working set - it's only because cache
is too eager to claim memory that is otherwise in use that
non-optimalities occur.


Well depends on what you mean by working set.

In our memory manager, there is a point where often used
"file cache" (ie. unmapped cache) is considered preferable
to unused or little used "application memory" (mapped
memory).

There will be a point where even the most swap phobic desktop
users will want to start swapping.

I missed the description of your exact problem... was it in
this thread somewhere? Testing 2.6 would be appreciated if
possible too.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/