Re: suspend processes at load (was Re: a simple OOM ...)

[Szabolcs Szakacsits <szaka@f-secure.com>]

On Thu, 19 Apr 2001, James A. Sutherland wrote:

> Rik and I are both proposing that, AFAICS; however it's implemented

Is it implemented? So why wasting words? Why don't you send the patch
for tests?

> since I think it could be done more neatly) you just suspend the
> process for a couple of seconds,

Processes are already suspended in __alloc_pages() for potentially
infinitely. This could explain why you see no progress and perhaps also
other people's problems who reported lockups on lkml. I run with a patch
that prevents this infinite looping in __alloc_pages().

So suspend at page level didn't help, now comes process level. What
next? Because it will not help either.

What would help from kernel level?

o reserved root vm, class/fair share scheduling (I run with the former
  and helps a lot to take control back [well to be honest, your
  statements about reboots are completely false even without too strict
  resource limits])

o non-overcommit [per process granularity and/or virtual swap spaces
  would be nice as well]

o better system monitoring: more info, more efficiently, smaller
  latencies [I mean 1 sec is ok but not the occasional 10+ sec
  accumulated stats that just hide a problem. This seems inrelevant but
  would help users and kernel developers to understand better a particular
  workload and tune or fix things (possibly not with the currently
  popular hard coded values).

As Stephen mentioned there are many [other] ways to improve things and I
think process suspension is just the wrong one.

> Indeed. It would certainly help with the usual test-case for such
> things ("make -j 50" or similar): you'll end up with 40 gcc processes
> being frozen at once, allowing the other 10 to complete first.

Can I recommend a real life test-case? Constant/increasing rate hit
to a dynamic web server.

	Szaka


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