Re: CALatencyLog?
Re: CALatencyLog?
- Subject: Re: CALatencyLog?
- From: Jeff Moore <email@hidden>
- Date: Tue, 14 Sep 2010 16:23:06 -0700
dtrace is kind of it's own thing. Out in user-space, I add static probes to my binaries and write dscripts that know how to interpret their data. Presumably (I've never done it), you'd have to do something similar with your kexts. Scripting dtrace is fairly straight forward for doing things like looking for events or profiling code.
Doing more advanced things like triggering other tools to do work would depend more on how good you are at shell scripting. Typically you end up piping the output of the dscript to something that interprets the results and triggers the other work you want done.
On Sep 14, 2010, at 4:07 PM, B.J. Buchalter wrote:
>
> On Sep 14, 2010, at 7:02 PM, Jeff Moore wrote:
>
>> The latency log code was a hack up we did based on the latency tool from the system_cmds project in Darwin. We removed it mostly because we hadn't been maintaining it as well as we should have after we started using dtrace to look at most performance issues.
>>
>> You may be able to recreate what you need with the old version of the CALatencyLog code you have and crossing it with a current version latency tool code in the current version of the system_cmds project.
>
> Well, maybe dtrace would be better than going down that road.
>
> The issue is that AFAIKT, dtrace does not "see" KEXTs. I need to instrument some stuff in my driver and pull it out. I have been using the chud signposts and doing a system trace in Shark (and the latency code also sees the kdebug entries that shark sees), but it is very difficult to interpret and visualize the things I am looking at with shark). Is there a way to get dtrace to trigger on and capture stuff that I am logging through the kdebug mechanism, thus allowing me to add visibility to the kext?
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