> -----Original Message----- > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx] > Sent: Saturday, November 4, 2017 4:05 AM > To: KY Srinivasan <kys@xxxxxxxxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>; olaf@xxxxxxxxx; Stephen > Hemminger <sthemmin@xxxxxxxxxxxxx>; jasowang@xxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; marcelo.cerri@xxxxxxxxxxxxx; > devel@xxxxxxxxxxxxxxxxxxxxxx; Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>; > leann.ogasawara@xxxxxxxxxxxxx > Subject: Re: [PATCH 10/17] hyper-v: trace vmbus_open() > > On Wed, Nov 01, 2017 at 05:43:08PM +0000, KY Srinivasan wrote: > > > > > > > -----Original Message----- > > > From: devel [mailto:driverdev-devel-bounces@xxxxxxxxxxxxxxxxxxxxxx] > On > > > Behalf Of Steven Rostedt > > > Sent: Tuesday, October 31, 2017 6:10 AM > > > To: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > > > Cc: olaf@xxxxxxxxx; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>; > > > jasowang@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > apw@xxxxxxxxxxxxx; > > > marcelo.cerri@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; Vitaly > > > Kuznetsov <vkuznets@xxxxxxxxxx>; leann.ogasawara@xxxxxxxxxxxxx > > > Subject: Re: [PATCH 10/17] hyper-v: trace vmbus_open() > > > > > > On Tue, 31 Oct 2017 13:48:00 +0100 > > > Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > I don't see how that information can be extracted easily without a > > > > > tracepoint here. Am I missing something? > > > > > > > > Wasn't one of the outcomes of the conference last week the fact that > for > > > > ftrace + ebpf we could get access to the structures of the function > > > > parameters? Or that work would soon be showing up? > > > > > > I told Linus that I'll start building an infrastructure on function > > > tracing to see what we can do. But it may be very limited in features. > > > I don't believe eBPF can follow arbitrary data structure pointers > > > without helper functions. Which doesn't exist for this type of code yet. > > > > > > > > > > > It just feels "wrong" to add a tracepoint for a function call, like it > > > > is a duplication of work/functionality we already have. > > > > > > We don't already have it. We may have something in a year (or two) that > > > may be able to get all the data that is requested here. But it's going > > > to take lots of RFC patch sets and brain storming to come up with > > > something that everyone is satisfied with. > > > > > > In other words, the functionality is currently in vaporware state. > > > > Greg, > > > > The added memory overhead is very minimal, and the added tracing > support is extremely useful for > > our debugging. If you don't mind, I would like to have this tracing support. > > Ok, it's your subsystem, you get to handle the long-term maintenance of > these :) > > Now merged, Thanks Greg. K. Y > > greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
