Messages in this thread | | | Date | Sun, 27 Oct 2002 14:29:19 +0100 | From | Manfred Spraul <> | Subject | Re: [PATCH,RFC] faster kmalloc lookup |
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I've run my slab microbenchmark over the 3 versions: - current - generic_fls - i386 asm optimized fls
The test reports the fastest time for 100 kmalloc calls in a tight loop (Duron 700). Loop/test overhead substracted.
32-byte alloc: current: 41 ticks generic_fls: 56 ticks bsrl: 54 ticks
4096 byte alloc: 84 ticks generic_fls: 53 ticks bsrl: 54 ticks
40 ticks difference for -current between 4096 and 32 bytes - ~4 cycles for each loop. bit scan is 10 ticks slower for 32 byte allocs, 30 ticks faster for 4096 byte allocs.
No difference between generic_fls and bsrl - the branch predictor can easily predict all branches in generic_fls for constant kmalloc calls.
-- Manfred
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