Re: [PATCH] no need to check for NULL before calling kfree() -fs/ext2/

[Arjan van de Ven]

On Fri, 2005-03-25 at 17:29 -0500, linux-os wrote:
> Isn't it expensive of CPU time to call kfree() even though the
> pointer may have already been freed? 

nope

a call instruction is effectively half a cycle or less, the branch
predictor of the cpu can predict perfectly where the next instruction is
from. The extra if() you do in front is a different matter, that can
easily cost 100 cycles+. (And those are redundant cycles because kfree
will do the if again anyway). So what you propose is to spend 100+
cycles to save half a cycle. Not a good tradeoff ;)

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