Re: [patch][rfc] acpi: do not use kmem caches

Christoph Hellwig
2008-12-01T17:18:06Z

On Mon, Dec 01, 2008 at 05:14:36PM +0300, Alexey Starikovskiy wrote:
> Why then you try to delete ACPICA code, which might be just disabled by
> undefining ACPI_USE_LOCAL_CACHE?
> If you do want to go that path, you need to create patch against ACPICA, not
> Linux code.

Sorry dude, but that's not how Linux development works. Please talk to
some intel OTC folks to get an advice on how it does.

>> Ah OK I misread, that's the cache's freelist... ACPI shouldn't be poking
>> this button inside the slab allocator anyway, honestly. What is it
>> for?
>>
> And it is not actually used -- you cannot unload ACPI interpreter, and
> this function is called only from there.

Care to remove all this dead code?

>> Is there a reasonable performance or memory win by using kmem cache? If
>> not, then they should not be used
> ACPI is still working in machines with several megabytes of RAM and
> 100mhz Pentium processors. Do you say we should just not consider them
> any longer?
> If so, then just delete all ACPICA caches altogether.

As Nick is trying to explain you for a while it's not actually going
to be a performance benefit for these, quite contrary because of how
slab caches waste a lot of memory when only used very lightly or not
at all.