Date: Thu, 14 Mar 2013 13:25:11 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: clock err in timers (alarm, status ...) and fix On Thu, Mar 14, 2013 at 10:08:46AM +0100, magnum wrote: > Solar, any comments? I haven't looked into this closely, but from Costin's posting it sounds like in jumbo you've misused timer ticks to implement jumbo's timeout feature. The timer ticks should not be used to measure prolonged periods of time where we care about precision. As to the 10 vs. 8 seconds discrepancy Costin observed, my guess is that he may be using a build with emulated timers (OS_TIMER is off, which it is on AMD GPU enabled builds and on Windows). With OS-provided timer ticks, I'd expect the imprecision to be a lot less than that (but still not good enough for the timeout feature). Core (aka "official JtR") only uses the timers for things where precision is not crucial. The worst, in terms of requiring some sort of precision, is the "Save = ..." setting in john.conf (how frequently to update the pot/rec/log files). Yes, it may be off by up to a factor of two on non-OS_TIMER builds. This is somewhat nasty, but I'm not sure if we care to address it. Alexander
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