Re: [PATCH] slub: reduce overhead of slub_debug

[Andi Kleen]

Christoph Lameter <cl@xxxxxxxxx> writes:


> +#ifdef __HAVE_ARCH_INV_MEMSCAN
> +void *inv_memscan(void *addr, int c, size_t size)
> +{
> +	if (!size)
> +		return addr;
> +	asm volatile("repz; scasb\n\t"

This will just do the slow byte accesses again internally.
scasb is not normally very optimized in microcode as far
as I know.

Also rep has quite some startup overhead which makes
it a bad idea for small sizes (<16-20 or so)

I would stay with the C version. I bet that one is 
faster.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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