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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This archive was generated by hypermail 2b29 : Thu Oct 31 2002 - 22:00:33 EST