Date: Sun, 5 Jul 2015 17:48:37 -0700 From: abhishek kulkarni <abhya007@gmail.com> To: Mark Johnston <markj@freebsd.org> Cc: Ryan Stone <rysto32@gmail.com>, Ryan Stone <rstone@freebsd.org>, "freebsd-dtrace@freebsd.org" <freebsd-dtrace@freebsd.org> Subject: Re: Regarding schedgraph.d Message-ID: <CAJUVseuHukeDRjWt27jm%2Bmkn1AqofQFqb5NgDZW9QJqmnUnxSQ@mail.gmail.com> In-Reply-To: <20150705233202.GA70385@raichu> References: <CAJUVsesOHQegeS=yfED8iKUoJK5KEVnLBqKH1MpSUuH_4i=_RQ@mail.gmail.com> <CAFMmRNwu8SoX-dJPb1wBh26UnXAnM5x7FZprDmXpVXbS7htkYQ@mail.gmail.com> <CAJUVseuHN-hLvLP6AQZdjwnQqpB24nSfm-dAWmn=j3y1EYiEMw@mail.gmail.com> <CAFMmRNy0AFBazEKR=QFY1h6htTre=Zi=dd==2c7Dkfc7BygZ%2BQ@mail.gmail.com> <20150705233202.GA70385@raichu>
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Thanks mark. I will go through all the references mentioned. your answer gives a clear picture of how the sched provider differs for FreeBSD. Thanks and Regards Abhishek Kulkarni On Sun, Jul 5, 2015 at 4:32 PM, Mark Johnston <markj@freebsd.org> wrote: > On Thu, Jul 02, 2015 at 07:40:21PM -0400, Ryan Stone wrote: > > The best that I can offer right now is the Illumos documentation: > > > > http://dtrace.org/guide/chp-sched.html > > I wrote and committed some DTrace provider man pages a little while ago. > The page for the sched provider is here: > > https://www.freebsd.org/cgi/man.cgi?query=dtrace-sched&sektion=4&apropos=0&manpath=FreeBSD+11-current > > > > > The caveat is that the types documented there are not implemented in > > FreeBSD. Where illumos uses a lwpsinfo_t, FreeBSD uses a struct thread: > > > > > https://svnweb.freebsd.org/base/head/sys/sys/proc.h?revision=284215&view=markup#l206 > > > > psinfo_t is replaced by struct proc. > > > > > https://svnweb.freebsd.org/base/head/sys/sys/proc.h?revision=284215&view=markup#l495 > > > > cpuinfo_t* arguments are not implemented and passed as NULL. You can > > access the current cpu number using the "cpu" variable. > > > > > > Finally, the schedctl-* probes don't apply to the FreeBSD scheduler and > > therefore are unimplemented. > > I removed them in r281702: our sched provider uses FreeBSD types and > thus is already incompatible with the Solaris/illumos sched provider, so > it didn't make much sense to me to keep them around. > > > > > > > On Thu, Jul 2, 2015 at 12:30 PM, abhishek kulkarni <abhya007@gmail.com> > > wrote: > > > > > Thanks Ryan. Those are some very useful tips. Ill get on with trying > all > > > of those and get back If I have some more concerns. Also, could you be > > > having some document which has some logical description about the > "sched" > > > probes for FreeBSD, which could give details like when is the > particular > > > probe fired, the probe's arguments etc. Thanks again. > > > > > > Regards > > > Abhishek Kulkarni > > > > > > On Wed, Jul 1, 2015 at 1:51 PM, Ryan Stone <rysto32@gmail.com> wrote: > > > > > >> On Tue, Jun 30, 2015 at 7:11 PM, abhishek kulkarni < > abhya007@gmail.com> > > >> wrote: > > >> > > >>> Hello Ryan, > > >>> > > >>> I was looking to schedgraph.d . I need to modify the script for a > > >>> single, particular thread. I atleast need to know the thread > transitions, > > >>> as in the context switches for the particular thread and also the > different > > >>> states for a single thread. Could you please help with the filters > that I > > >>> need to add in order to use the script for a single thread or else > suggest > > >>> me just the nexessary probes that I could use for writing a new > script for > > >>> a single thread . > > >>> > > >>> Regards > > >>> Abhishek Kulkarni > > >>> > > >> > > >> There are a couple of things that you could filter on, depending on > what > > >> you know about the thread of interest. The "execname" variable gives > the > > >> name of the current process. If you're interesting in tracing a > > >> single-threaded process, that would be an option. Another variable of > > >> interest would be the "curthread" variable. This gives a pointer to > the > > >> "struct thread" for the current thread. One field that you could > trace on > > >> would be curthread->td_tid. You can use ps to find your thread id > and then > > >> run the script as: > > >> > > >> dtrace -s script.d <tid> > > >> > > >> And in the script, filter with / curthread->td_tid == $1 /. Another > > >> field that you could use would be curthread->td_name, which contains > the > > >> name of the current thread. If your application names threads with > > >> "pthreads_set_name_np()", then that name will appear in td_name and > you can > > >> filter based off of that. > > >> > > >> An alternative approach would be to use a thread-local variable. If > you > > >> know that your thread is the only thread that might hit a probe, you > can > > >> set a thread local variable in that probe and filter on it later on. > For > > >> example, if your thread is the only thread that will call a function > called > > >> foobar() in the kernel, you could do this: > > >> > > >> fbt::foobar:entry > > >> { > > >> self->interesting = 1; > > >> } > > >> > > >> sched:::off-cpu > > >> / self->interesting / > > >> { > > >> /* trace interesting data here */ > > >> } > > >> > > >> > > > > > _______________________________________________ > > freebsd-dtrace@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-dtrace > > To unsubscribe, send any mail to "freebsd-dtrace-unsubscribe@freebsd.org > " >
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