Re: [PATCH 03/11] vfs: Don't allow overwriting mounts in the current mount namespace

[Eric W. Biederman]

Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> writes:

> On Tue, 18 Feb 2014 14:20:29 -0800 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> For this kind of function return value it actually tends to work very
>> well, and in fact often generates slightly better code than "int". So
>> I don't _hate_ bool, and we've certainly had a lot more use creep in
>> lately, but I also don't really see "bool" as much of an upside.
>
> And in function declarations, it makes it very obvious that the function
> is not one of our "return 0 or -ERROR" ones.

So I played with this instance in particular.  The only difference winds
up being by the bool version uses byte instructions on %al and %bl
instead of their 32 bit interger equivalents on %eax and %ebx.

I also benchmarked the difference and on the most sensitive test I could
find.  will-it-scale/unlink2 (aka create,close,unlink each process in a
separate directory).  There were no measurable performance differences.

So for purposes of better documentation I have changed the function, and
I will repost my patches shortly.

Eric
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/