Date: Tue, 3 May 2011 08:04:52 -0400 From: John Baldwin <jhb@freebsd.org> To: Alexander Leidinger <Alexander@leidinger.net> Cc: Kostik Belousov <kostikbel@gmail.com>, arch@freebsd.org Subject: Re: [PATCH] Add ktrace records for user page faults Message-ID: <201105030804.52840.jhb@freebsd.org> In-Reply-To: <20110503133844.184523llr0156o9w@webmail.leidinger.net> References: <201105021537.19507.jhb@freebsd.org> <201105021602.02668.jhb@freebsd.org> <20110503133844.184523llr0156o9w@webmail.leidinger.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tuesday, May 03, 2011 7:38:44 am Alexander Leidinger wrote: > Quoting John Baldwin <jhb@freebsd.org> (from Mon, 2 May 2011 16:02:02 -0400): > > > It is true that it would be nice to have the exact faulting address, though > > having page granularity has been sufficient for the few times I've actually > > used the address itself (e.g. I could figure out which page of libstdc++ a > > fault occurred on and narrow down from there as to which of the routines most > > likely was executed given what the app was doing at the time). In my case > > knowing how much time was spent handling a page fault has been useful. > > > > Would we have to push this logic out of vm_fault and into every > > trap() routine > > to get the original address? That would make the patch quite a bit bigger > > (touching N MD files vs 1 MI file). > > dtrace is not a solution here (in general, not to the exact-address problem)? It probably is, but many folks are still quite used to ktrace. At some point I may sit down and spend more time with DTrace, but for now I have other fish to fry. I can just keep the page fault tracing patch private if that is what folks prefer. -- John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201105030804.52840.jhb>