Re: [RFC] speeding up the stat() family of system calls...

From: H. Peter Anvin
Date: Fri Dec 27 2013 - 18:30:57 EST

On 12/26/2013 10:09 PM, H. Peter Anvin wrote:
> On 12/26/2013 11:00 AM, Linus Torvalds wrote:
>> Interestingly, looking at the cp_new_stat() profiles, the games we
>> play to get efficient range checking seem to actually hurt us. Maybe
>> it's the "sbb" that is just expensive, or maybe it's turning a (very
>> predictable) conditional branch into a data dependency chain instead.
>> Or maybe it's just random noise in my profiles that happened to make
>> those sbb's look bad.
> Much to my surprise, this patch adds almost 10K of text to an
> "allyesconfig" build. I wouldn't have expected it. I'll look at it
> some more tomorrow.

Mystery solved... it is all code added by gcov &c because a new (inline)
function is added to the code base. So it is fluff, not real.


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