From owner-freebsd-dtrace@freebsd.org Sun Jul 5 23:32:10 2015 Return-Path: Delivered-To: freebsd-dtrace@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 37F97A14E for ; Sun, 5 Jul 2015 23:32:10 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: from mail-pa0-x230.google.com (mail-pa0-x230.google.com [IPv6:2607:f8b0:400e:c03::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 05B771FAB; Sun, 5 Jul 2015 23:32:09 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: by pacws9 with SMTP id ws9so86560649pac.0; Sun, 05 Jul 2015 16:32:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=Rt4ikT/eq29V375GofD7UMebLIRq/fl/tLscCtU9NJU=; b=gr4WpzwS0gufVkmF0vayzv1LN/racmCxvW2xc69UB4uaN7J+cF1cE9JDPbpa00t7Yp cdNnw/5gGfHE4OiIeVTExuupHS/Etu4Ld9K4uw2NKYKNg5kGhQUy/wEvgycYFGrSM0BC HfooNrCO04HnaPRaEvl0oOCjhQEkWJrD3HntwwnBOBFOnxlKHxDzKTJai0J8tKgLcikR 1cJ9XxJp5etBs6DKWNO4lnZ5YoodOILAl4vAl0vk0D+8FnNW9JF1A9xexMqF0AaVln6V EFhLOiM8X1VXioaXf+JHE+bR+KE39kzeriHRBwsmOkmsHHB+7YVWR6JrNRAeAaMsm9ea eOlA== X-Received: by 10.70.128.226 with SMTP id nr2mr39197843pdb.139.1436139129045; Sun, 05 Jul 2015 16:32:09 -0700 (PDT) Received: from raichu ([104.232.114.184]) by mx.google.com with ESMTPSA id p1sm15997112pdb.3.2015.07.05.16.32.06 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 05 Jul 2015 16:32:07 -0700 (PDT) Sender: Mark Johnston Date: Sun, 5 Jul 2015 16:32:02 -0700 From: Mark Johnston To: Ryan Stone Cc: abhishek kulkarni , Ryan Stone , "freebsd-dtrace@freebsd.org" Subject: Re: Regarding schedgraph.d Message-ID: <20150705233202.GA70385@raichu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-BeenThere: freebsd-dtrace@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "A discussion list for developers working on DTrace in FreeBSD." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Jul 2015 23:32:10 -0000 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 > 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 wrote: > > > >> On Tue, Jun 30, 2015 at 7:11 PM, abhishek kulkarni > >> 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 > >> > >> 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"