Re: [PATCH] patch-slab-split-03-tail

[Anton Blanchard]

> <<<<<<<
> An object cache's CPU layer contains per-CPU state that must be 
> protected either by per-CPU locking or by disabling interrupts. We 
> selected per-CPU locking for several reasons:
> [...]
>  x    Performance. On most modern processors, grabbing an uncontended 
> lock is cheaper than modifying the processor interrupt level.
> <<<<<<<<
> 
> Which cpus have slow local_irq_disable() implementations? At least for 
> my Duron, this doesn't seem to be the case [~ 4 cpu cycles for cli]

Rusty did some tests and found on the intel chips he tested
local_irq_disable was slower. He posted the results to lkml a few weeks
ago.

On ppc64 it varies between chips.

Anton