On Wed, Sep 9, 2009 at 5:10 PM, Joel Reymont<joe...@gmail.com> wrote: > I added a couple of static probes to Firefox to measure actual work done. I > could have used a pid$target probe with a function name but work is done > within an if statement, which is where I placed the static probes. > > I'm wondering about my use, though. Is the following significantly more > efficient than pid$target::FunName:entry and return? >
No, it's not significantly more efficient. Both function entry/return probes and USDT probes involve replacing an instruction in the stream with a trap instruction. The expense of the trap into the kernel is going to overwhelm any subtleties in handling between the two different types of probes. > I heard somewhere that $target does not need to be used with static probes > but the probes don't show up unless Firefox is running and then only as > mozillaNNNNN, i.e. mozilla$target. > Nope, you'll need $target. Both the pid and USDT probes manipulate the target process, so they need some way of identifying that process. Chad _______________________________________________ dtrace-discuss mailing list dtrace-discuss@opensolaris.org
