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

From: Stephan von Krawczynski (
Date: Fri Jan 04 2002 - 08:03:21 EST

On Thu, 3 Jan 2002 23:26:01 -0600
Ken Brownfield <> wrote:

> On Fri, Jan 04, 2002 at 01:19:28AM +0100, Stephan von Krawczynski wrote:
> | > A) VM has major issues
> |
> | On all boxes I run currently (all 1GB or below RAM), I cannot find
> | _major_ issues.
> Yeah, I'm seeing it primarily with 1-4GB, though I have very few <1GB
> machines in production.

Ok. It would be really nice to know if the -aa patches do any good at your
configs. Andrea has possibly done something on the issue. But let me take this
chance to state an open word: last time Andrea talked about his personal
hardware I couldn't really believe it - because it was so ridiculously small. I
wonder if anyone at SuSE management _does_ actually read this list and think
about how someone can do a good job without good equipment. If you really want
to do something groundbreaking about highmem you have to have a _box_. A box
_somewhere_ in the world or a patch for highmem-in-lowmem is not really the
same thing. Even Schumacher wouldn't have won formula one by sitting inside a
Fiat Uno with a patched speedometer.

> but I
> do think the mindset behind the kernel needs to at least partially break
> free of the grip of UP desktops, at least to the point of fixing issues
> like I'm mentioning.
> Not critical for me; but high-profile on lkml.

You are right.

> [...]
> | > C) IO-APIC code that requires noapic on any and all SMP
> | > machines that I've ever run on.
> |
> | I am currently running 5 Asus CUV4X-D based SMP boxes all with apic
> | _on_, amongst which are squids, sql servers, workstation type setups
> | (2 my very own).
> Do they have *sustained* heavy hit/IRQ/IO load? For example, sending
> 25Mbit and >1,000 connections/s of sustained small images traffic
> through khttpd will kill 2.4 (slow loss of timer and eventual total
> freeze) in a couple of hours. Trivially reproducable for me on SMP with
> any amount of memory. On HP, Tyan, Intel, Asus... etc.

Hm, I have about 24GB of NFS traffic every day, which may be too less. What
exactly are you seeing in this case (logfiles etc.)?

> It's not that the kernel is bad, it's that there are specific things
> that shouldn't be forgotten because of a "the kernel is good"
> evaluation.

Hopefully nobody does this here, I don't.

> Like I said, I suspect that most people with machines in lower-load
> environments don't have these issues, but "number of people effected" is
> only one metric to judge the importance of an issue.

The number of people is not really interesting for me, as the boxes get bigger
every day it is only a matter of time to see more people with lots of GB (as an

> Of course, I'm not biased or anything. ;-)

How could you ? ;-))


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