From 7a135166f65232a39d1a607465bbd26ac993069a Mon Sep 17 00:00:00 2001 From: Neal Norwitz Date: Sun, 13 Jun 2004 20:45:11 +0000 Subject: SF patch #969180, hotshot incorrectly computes elapsed time by Jason Beardsley. If the seconds are different, we still need to calculate the differences between milliseconds. Also, on a Gentoo Linux (2.6.5) dual Athlon MP box with glibc 2.3, time can go backwards. This probably happens when the process switches the CPU it's running on. Time can also go backwards when running NTP. If we detect a negative time delta (ie, time went backwards), return a delta of 0. This prevents an illegal array access elsewhere. I think it's safest to *not* update prev_timeofday in this case, so we return without updating. Backport candidate. --- Modules/_hotshot.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/Modules/_hotshot.c b/Modules/_hotshot.c index a04494f..0683be6 100644 --- a/Modules/_hotshot.c +++ b/Modules/_hotshot.c @@ -820,12 +820,14 @@ get_tdelta(ProfilerObject *self) GETTIMEOFDAY(&tv); - if (tv.tv_sec == self->prev_timeofday.tv_sec) - tdelta = tv.tv_usec - self->prev_timeofday.tv_usec; - else - tdelta = ((tv.tv_sec - self->prev_timeofday.tv_sec) * 1000000 - + tv.tv_usec); + tdelta = tv.tv_usec - self->prev_timeofday.tv_usec; + if (tv.tv_sec != self->prev_timeofday.tv_sec) + tdelta += (tv.tv_sec - self->prev_timeofday.tv_sec) * 1000000; #endif + /* time can go backwards on some multiprocessor systems or by NTP */ + if (tdelta < 0) + return 0; + self->prev_timeofday = tv; return tdelta; } -- cgit v0.12