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From: Alan Cox <alan@redhat.com>
To: akpm@zip.com.au (Andrew Morton)
Cc: rml@tech9.net (Robert Love),
	torvalds@transmeta.com, riel@conectiva.com.br,
	linux-kernel@vger.kernel.org, alan@redhat.com
Subject: Re: [PATCH] 2.5.28: VM strict overcommit
Date: Thu, 25 Jul 2002 04:18:14 -0400 (EDT)	[thread overview]
Message-ID: <200207250818.g6P8IFU22876@devserv.devel.redhat.com> (raw)
In-Reply-To: <3D3F6EBB.3B7817C5@zip.com.au> from "Andrew Morton" at Jul 24, 2002 08:21:31 PM

> 		if (!vm_enough_memory((maxpos - inode->i_size) >> PAGE_SHIFT)) {
> 			err = -ENOMEM;
> 			goto out_nc;
> 		}
> 	}
> 
> tmpfs supports holes.  Looks to me like a small write which creates
> a big hole will be severely over-accounted for?

Intentionally. The base tree doesn't support page cache removal AS callbacks
so cannot support the ideal behaviour. The other rounding bits for the
tmpfs stuff are I think all fixed in 2.4 by Hugh's stuff, but fixing 2.5
tmpfs is an ongoing seperate project.

> vm_enough_memory() looks really slow.  I'll bench this a bit.

On the benches I've run I can't see any difference whatever the
accounting mode I am using. 

> of memory is dirty" is junk.  It really wants to know more
> information about the dynamic state of the system.  So tracking
> all those datums on-the-fly would be handy.  One day.

We need it three years ago not "one day"

Alan

      reply	other threads:[~2002-07-25  8:15 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-07-25  0:29 [PATCH] 2.5.28: VM strict overcommit Robert Love
2002-07-25  3:21 ` Andrew Morton
2002-07-25  8:18   ` Alan Cox [this message]

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