Messages in this thread | | | Date | Thu, 09 Apr 2009 10:11:48 +0800 | From | Li Zefan <> | Subject | Re: Multiple Tracers |
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CC: Arnaldo Carvalho de Melo <acme@redhat.com>
Ingo Molnar wrote: > * Steven Whitehouse <swhiteho@redhat.com> wrote: > >> Hi, >> >> On Wed, 2009-04-08 at 15:53 +0200, Ingo Molnar wrote: >>> * Steven Whitehouse <swhiteho@redhat.com> wrote: >>> >>>> Hi, >>>> >>>> A little while back I posted a RFC patch which added gfs2 glock >>>> tracing to blktrace. There was a suggestion that I should look >>>> instead at the generic tracing code and add a new tracer, but I've >>>> come up with a couple of issues along the way. >>>> >>>> I think from what I can see that its only possible to run a single >>>> tracer at once, so running blktrace (for example) would preclude >>>> me from also tracing gfs2's glocks at the same time. Also, I can >>>> see no mechanism by which I could ensure the sequencing between >>>> the blktrace and glock traces other than exporting the blktrace >>>> sequence number, even if running multiple tracers at the same time >>>> was possible. >>> There's a recent addition: the EVENT_TRACE() facility. Would that >>> suit your purposes? >>> >>> Ingo >> If I can get both blktrace and glock trace info from it, then yes. >> I thought that the blktrace output went either via the original >> relayfs path, or via its own tracer so that it wasn't possible to >> use it and the event trace facility at the same time, unless I use >> blktrace via relayfs. From what I've read I thought that probably >> the relayfs interface for blktrace might eventually be removed in >> favour of the generic tracing interface, but I'm not 100% sure of >> that, so perhaps someone can confirm the plans in that area? > > Tom Zanussi (Cc:-ed) recently converted the blktrace tracepoints to
I guess you mean Arnaldo <acme@redhat.com> ;)
> a tracing framework - and i think much of that could be reused to > add EVENT_TRACE() tracepoints to blktrace too. > > Tom, what's your take on this? > > In general, this is the direction we want to take: EVENT_TRACE() > tracepoints that can be used in a generic way, in any tracer. >
Actually we've planed to do this, and for other tracers.
-- Zefan
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