On Sat Dec 15 09:01:00 2007, TELS wrote:
Show quoted text> On Tue Nov 27 12:11:20 2007, JIK wrote:
> > As described in
http://rt.cpan.org//Ticket/Display.html?id=31006, we
> > encountered a huge Math-BigInt performance regression when upgrading
> > from RHL9 to CentOS 5. In RHL9, the Math-BigInt version was 1.63; in
> > CentOS 5, it's 1.77. I also tried the current version of Math-BigInt,
> > Math-BigRat and bignum, and they had the same problem, so I assume that
> > everything between 1.77 and 1.87 has this problem. You can reproduce
> > the issue by invoking the function mentioned in that bug report; it
> > takes a packed 8-byte integer, most significant byte first, which
> > specifies the number of 100-nanosend intervals which have passed since
> > January 1, 1601 (ugh!).
>
> Sorry for not getting back earlier to you, I didn't get (once again
> *sigh*) the email from RT.
>
> Looking at the other bug report, I do not see an easy testcase, can you
> please create some (very) short testcase that I can run and see why it
> gets so much slower?
>
> A simple "$x = -$y" shouldn't get slower by an order of magnitude.
>
>
Okay, sorry, I negleted to actually look at your patch and it is now
clear why this slowdown happens:
In old versions of BigInt, int() was not overloaded and thus the result
was always truncated to a Perl scalar (effectively what numify() does).
You patch basically restores that behaviour, truncating the result
manually to a Perl scalar and thus making the subsequent calculations
going faster.
In general, use BigInt objects only if neccessary as they are quite slow
(sorry about this - wish I could make them faster).
--- Storage_Lite.pm.orig 2007-11-27 11:07:36.625000000 -0500
+++ Storage_Lite.pm 2007-11-27 11:08:27.843750000 -0500
@@ -1326,7 +1326,13 @@
my $iHSec = $iBigDt % 10000000;
$iBigDt /= 10000000;
my $iBigDay = int($iBigDt / (24*3600)) + 1;
+ if ($iBigDay->numify eq $iBigDay) {
+ $iBigDay = $iBigDay->numify;
+ }
my $iTime = int($iBigDt % (24*3600));
+ if ($iTime->numify eq $iTime) {
+ $iTime = $iTime->numify;
+ }
#2. Year->Day(1601/1/2?)
$iDt = $iBigDay;
$iYear = 1601;
