Re: [PATCH] Re: simple FS application that hangs 2.4-test5, mem mgmt problem or FS buffer cache mgmt problem?

From: Rik van Riel (
Date: Wed Aug 02 2000 - 18:12:45 EST

On Thu, 3 Aug 2000, Roger Larsson wrote:

> One thing to remember.
> Working limits are lowered due to not running kswapd until ALL
> zones have zone_wake_kswapd.

Which is OK, since at that point we still have the
difference between pages_low and pages_min to go
before allocations get _throttled_.

NOTE: this should only affect system *performance*,
never stability!

> Maybe limits need to be refined (linux/mm/page_alloc.c)
This word should tip you off that the patch below really
doesn't make much sense...

Rule of thumb: if you can't explain _why_ it makes sense,
it probably doesn't.

> This has lead me to the conclusion that kswapd can't be made
> to handle the most intensive loads. It is easy force yourself
> into a situation where both zone_wake_kswapd and low_on_memory
> are set for all zones...

I guess that means that either kswapd is going back to sleep
without getting any work done, or kswapd isn't scheduled in
when it should be.

Changing the limits will mean it's _harder_ to get into the
same situation, but it really doesn't do anything to actually
*fix* the problem. The problem being that kswapd doesn't get
run or doesn't free pages as fast as it should when we try to
wake it up.

(or kswapd going to sleep too soon? IMHO it should go to sleep
only when *all* zones have zone->free_pages > zone->pages_low
and at least one zone has zone->zone_wake_kswapd cleared)



"What you're running that piece of shit Gnome?!?!"
       -- Miguel de Icaza, UKUUG 2000

- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to Please read the FAQ at

This archive was generated by hypermail 2b29 : Mon Aug 07 2000 - 21:00:09 EST