Date: Tue, 20 Dec 2016 08:08:05 +0900 From: Hiroki Sato <hrs@allbsd.org> To: Domagoj Stolfa <domagoj.stolfa@gmail.com> Cc: freebsd-arch@FreeBSD.org, adrian.chadd@gmail.com Subject: Re: RFC: DTrace probes for debugging or testing in userland programs Message-ID: <9887B4D9-A336-498D-ADDE-E683B0DEC2E8@allbsd.org> In-Reply-To: <20161219215425.GB42198@freebsd-laptop> References: <20161220.043646.1181938468712455328.hrs@allbsd.org> <CAJ-Vmon3%2BjMyfgBcVORyMoXX3JEAFCWtK2VPo9wWLN2hsS%2BrNA@mail.gmail.com> <20161219204719.GE65993@freebsd-laptop> <20161220.060542.16356944875657261.hrs@allbsd.org> <20161219215425.GB42198@freebsd-laptop>
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2016/12/20 6:54=1B$B!"=1B(BDomagoj Stolfa <domagoj.stolfa@gmail.com> =1B$B$N= %a%C%;!<%8=1B(B: > Hello, >=20 >> To be clear: my proposal is to replace only debug logging (i.e. for >> developers), not the other logging in general, as the subject line >> says. Although I agree that DTrace is not lightweight, I think >> impact of just adding tracing probes is small. >>=20 >> -- Hiroki >=20 > I believe this would indeed be beneficial for debugging. My main concern > is the way that we would have to attach to probes should we use SDT > provider as it works now. If we were to create probes for each of the > daemons, which we would then run individually, and if I'm not mistaken, > that would spawn 2 times the amount of processes than are currently=20 > spawned due to each ``dtrace'' call from the command line spawns a process= . No. A single dtrace process can catch fired probes of multiple processes if you want. Filtering probes or the results from probes is things which should be done in the D script level, not in the target binary, in the case of DTrace. My proposal does not cover how to use the probes. It just provides probes and a sample script to reproduce the (almost) same results with printf() debug logging. The big difference is that a developer can use these probes for a more complex debug script and/or regression test script because the probes can carry data structures in question, not just a string. -- Hiroki=
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