Re: why are conditional breakpoints SO SLOW?
Re: why are conditional breakpoints SO SLOW?
- Subject: Re: why are conditional breakpoints SO SLOW?
- From: email@hidden
- Date: Wed, 19 Mar 2014 11:16:31 -0700
Remember also that a stop in Xcode involves a system trap in the debugee which causes the send of a mach message to debugserver, then a bunch of (select based) communication back & forth between debugserver & Xcode, then a system trap whereby debugserver restarts the target. And if the condition involves a function call (the original example did not) we actually go through this process several times per breakpoint hit. This is not multitasking speed stuff, this is IPC speed stuff, and not just one message per stop...
Jim
On Mar 18, 2014, at 10:30 AM, Scott Ribe <email@hidden> wrote:
> On Mar 18, 2014, at 11:02 AM, Quincey Morris <email@hidden> wrote:
>
>> Even if there are several context switches involved, are we saying that a context switch takes 200,000 or so CPU cycles? Multitasking wouldn’t be feasible if it were that slow.
>
> Multitasking does not switch contexts nearly as often as what we're talking about in this case.
>
> --
> Scott Ribe
> email@hidden
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> (303) 722-0567 voice
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