Messages in this thread | | | Subject | Re: useful LKM? | From | Andi Kleen <> | Date | 02 Oct 1997 11:33:00 +0200 |
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Jacques Gelinas <jack@solucorp.qc.ca> writes:
> Ultimatly, this optimisation could even be a compile time option > > [ ] Squeeze as much memory as need > > struct foo { > . > #if define(KERNEL_OPTION) || !defined(KERNEL_SQUEEZE) > struct sub_foo *pt; > #endif > . > }; Often is doesn't matter anyways, because the kmalloc() Linux uses always rounds the block size to the next power of 2. Only when this additional field causes the structure size to go into the next 'order' (e.g. from 32 to 64 bytes) it'll cost you memory. The kmalloc emulation on top of slab in 2.1 is power-of-2 based too, if you use slap directly the effect is still there (because slab aligns the objects in the page for the cache colouring), but much less. Most structures in Linux are still managed by kmalloc() though..
-Andi
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