Date: Thu, 7 Jun 2012 16:42:41 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-arch@freebsd.org Cc: Attilio Rao <attilio@freebsd.org>, Alexander Leidinger <Alexander@leidinger.net>, Adrian Chadd <adrian@freebsd.org>, Dag-Erling@freebsd.org, grav <des@des.no> Subject: Re: KTR_SPAREx Message-ID: <201206071642.41216.jhb@freebsd.org> In-Reply-To: <20120607220933.00003865@unknown> References: <86bokyvtc2.fsf@ds4.des.no> <CAJ-FndAjcfd21xwYHPrSxgz32eHp2xTGRao1Kyqx4yBZTPD94A@mail.gmail.com> <20120607220933.00003865@unknown>
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On Thursday, June 07, 2012 4:09:33 pm Alexander Leidinger wrote: > On Tue, 5 Jun 2012 21:14:02 +0100 Attilio Rao <attilio@freebsd.org> > wrote: > > > 2012/6/5 Adrian Chadd <adrian@freebsd.org>: > > > Hi, > > > > > > I'm very tempted to make if_ath use KTR_DEV, but then have an extra > > > ath sysctl which does something like: > > > > > > if (sc->sc_ktr_enable) > > > KTR(); > > > > But the actual problem is that your output will be overwhelmed by the > > clutter of all the other KTR_DEV consumers. > > > > We very much need an much higher granularity on KTR classes and > > possibly a way to use it on-the-fly for kernel development and I think > > what I suggested earlier makes sense. > > How much of the uncovered uses of KTR really need KTR (instead of > dtrace)? How many of them are time critical enough that dtrace is not > fast enough? How many of them need to run very early so that not enough > kernel infrastructure is available to run dtrace (can we run dtrace > scripts very early during boot (when enough kernel infrastructure is > available, before anything in userland starts) like in Solaris)? Can you run a dtrace script from ddb? (Hint: you can run 'show ktr' from DDB, and you can use ktrdump on a crash dump to get a timeline of events when doing post-mortem analysis.) -- John Baldwin
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