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Re: memory usage

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On Aug 20, 2007, at 12:26 AM, Thomas Bushnell BSG wrote:

On Mon, 2007-08-20 at 02:52 +0200, Samuel Thibault wrote:
Samuel Thibault, le Mon 20 Aug 2007 02:18:44 +0200, a écrit :
Samuel Thibault, le Mon 20 Aug 2007 02:06:18 +0200, a écrit :
int             vm_object_cached_max = 200;    /* may be patched*/

We should probably raise it in debian at least.

I've made it 2000.

That put a simple gnumach compilation time from 4m18 down to 3m48. The number of cached objects indeed raised to 2000 during the compilation.
(note: these are the cached objects, not the currently used objects).

1: I think it should be raised in gnumach itself, not just in the Debian

I agree. The value should also be dymanically changeable by the
user if possible (I am not familiar enough with the code in question
to know what is or isn't possible). At the very least, it should be changable
via a boot-time argument to mach

2: It should be raised to be very high indeed; I think it should be
considerably more than the number of currently used objects in a system
under normal load; otherwise paging requires initializing the object,
which is a pointless hit.

Too high, and you can end up wasting memory caching object that are
very unlikely to be used again. THat being said, there is no problem holding all those objects in cache as long as they are deallocated on the fly if/when
memory is needed.

3: Doing (2), it seems to me, should best be done by something dynamic
based upon the memory available to the kernel.

See above :-)


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