Re: [patch] ipc updates
Andi Kleen (ak@muc.de)
Sun, 7 Nov 1999 19:45:04 +0100
On Sun, Nov 07, 1999 at 07:20:08PM +0100, Manfred Spraul wrote:
> Andi Kleen wrote:
> >
> > As far as I can see it still has the resource race (resources are charged
> > after sleeping without rechecking, so there is a window where the user is
> > able to overcommit). Here is for reference my 2.2 patch that fixes the
> > problem and Scott Maxwell's DoS.
> >
>
> I think my patch solves both problems:
> * the overcommit race does not exist: the code never sleeps between
> checking for free queue space and increasing q_cbytes.
Yes, sorry, seems I misread your new code.
> I reuse the number of bytes in the queue. This allows the user to
> overcommit by ~ 3%, IMHO that's acceptable.
> (16384 one byte messages eat ~ 512 kB kernel memory, 2 8 Kb message +
> 16382 0 byte messages around 528 kB)
>
That's a lot. Hopefully Linux will have the beancounter patches someday.
-Andi
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