Instruments: Time Profiler vs Sampler
Instruments: Time Profiler vs Sampler
- Subject: Instruments: Time Profiler vs Sampler
- From: BJ Homer <email@hidden>
- Date: Wed, 9 Dec 2009 23:44:13 -0700
In Snow Leopard, Apple added the Time Profiler instrument to Instruments. It appears to have similar functionality as the Sampler instrument that existed in Leopard. The template for for Time Profiler says it "performs low-overhead time-based sampling" of processes. The CPU Sampler template has a similar description, but does not include the phrase "low-overhead." This suggests that Time Profiler is essentially a better version of the Sampler instrument.
My original question was "why does the Sampler instrument still exist", but I've since found that Time Profiler won't work on attached iPhone devices, where Sampler will. This is reflected in the template chooser; the Time Profiler template is present when the OS X -> All option is selected on the left, but not when iPhone -> All is selected. I'm curious, though, why the CPU Sampler template (which uses the older Sampler instrument) is still included when OS X is selected.
So my real question is this: is there anything Sampler can do that Time Profiler can't? Any reason to use the Sampler instrument when developing for OS X? At first I thought that Time Profiler didn't have the option to sample sleeping threads, but it turns out it's available through the "info" button on the instrument once you've added it. Time Profiler makes you decide whether you want to sample running threads before you start profiling, while Sampler just always does it and lets you filter out non-running threads later if you want. A small win for Sampler, perhaps, but hardly worth having two separate instruments.
Is there something else I'm missing?
-BJ
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