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Even if it is empty string there will be performance downgrade in case
if strlen not inline function.<br>
<br>
because when call will be issued, CPU will flush internal pipeline and
then will try get if from<br>
cache. If it's not already in L1 cache it will be cache miss, and it
will try to get it from L2 cache,<br>
or even from memory, and that will be really slow. In this case you can
easily lost few<br>
tens of thousands on CPU cycles.<br>
<br>
All the Best!<br>
Sergey.<br>
<br>
<br>
joachim wrote:
<blockquote cite="mid41EE6D7E.6080306@securax.org" type="cite">If its a
0x00 it will stop yes, but if its not, it will continue, while
<br>
its not necessary as we already know the string is not zero length.
<br>
<br>
Which would mean that if the stringlength = 0, there will be no waste
of
<br>
cpu cycles, if its 1 char or more, it will waste cpu cycles.
<br>
<br>
If the string is 255 chars, it will use up around 255 times more cpu
<br>
cycles if you use the strlen.
<br>
<br>
<br>
Zoa.
<br>
<br>
<br>
Andrew Kohlsmith wrote:
<br>
<br>
<blockquote type="cite">On January 19, 2005 07:45 am, Jerris, Michael
MI wrote:
<br>
<br>
<br>
<blockquote type="cite">It would probably be more efficient to
check just the first char of the
<br>
string to see if it is 0 than to loop through the whole string to see
if
<br>
it is > 0 length.
<br>
<br>
<br>
</blockquote>
<br>
But would strlen()'s loop not terminate on the first 0x00 char?? I
mean a
<br>
couple dozen cycles here is not something a user's gonna notice, even
in a
<br>
tight loop that is processing strings for Asterisk.
<br>
<br>
Personally I feel this whole ast_strlen_zero macro (it better be a
macro or at
<br>
least inline function!) is poor optimization -- does Asterisk really
spend so
<br>
much time in strlen() that it was necessary?
<br>
<br>
-A.
<br>
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