Re: [patch] adjustments to dirty memory thresholds

[Andrew Morton <akpm@zip.com.au>]

William Lee Irwin III wrote:
> 
> On Tue, Aug 27, 2002 at 09:39:09PM -0700, Andrew Morton wrote:
> > These ratios are scaled so that as the highmem:lowmem ratio goes
> > beyond 4:1, the maximum amount of allowed dirty memory ceases to
> > increase.  It is clamped at the amount of memory which a 4:1 machine
> > is allowed to use.
> 
> This is disturbing. I suspect this is only going to raise poor memory
> utilization issues on highmem boxen.

The intent is to fix them.  Allowing more than 2G of dirty data to
float about seems unreasonable, and it pins buffer_heads.

But hey.  The patch merely sets the initial value of /proc/sys/vm/dirty*,
and those things are writeable.

> Of course, "f**k highmem" is such
> a common refrain these days so that's probably falling on deaf ears.

On the contrary.

> AFAICT the OOM issues are largely a by-product of mempool allocations
> entering out_of_memory() when they have the perfectly reasonable
> alternative strategy of simply waiting for the mempool to refill.

I don't have enough RAM to reproduce this.  Please send
call traces up from out_of_memory().