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From: Steven Rostedt <rostedt@goodmis.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: olaf@aepfle.de, sthemmin@microsoft.com, jasowang@redhat.com,
	linux-kernel@vger.kernel.org, marcelo.cerri@canonical.com,
	apw@canonical.com, devel@linuxdriverproject.org,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	leann.ogasawara@canonical.com
Subject: Re: [PATCH 10/17] hyper-v: trace vmbus_open()
Date: Tue, 31 Oct 2017 09:10:28 -0400	[thread overview]
Message-ID: <20171031091028.7fa53a97@gandalf.local.home> (raw)
In-Reply-To: <20171031124800.GA27947@kroah.com>

On Tue, 31 Oct 2017 13:48:00 +0100
Greg KH <gregkh@linuxfoundation.org> 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.

-- Steve

  reply	other threads:[~2017-10-31 13:10 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-29 19:20 [PATCH 00/17] Drivers: hv: vmbus: Add tracing to VMBus kys
2017-10-29 19:21 ` [PATCH 01/17] hyper-v: trace vmbus_on_msg_dpc() kys
2017-10-29 19:21   ` [PATCH 02/17] hyper-v: trace vmbus_on_message() kys
2017-10-29 19:21   ` [PATCH 03/17] hyper-v: trace vmbus_onoffer() kys
2017-10-29 19:21   ` [PATCH 04/17] hyper-v: trace vmbus_onoffer_rescind() kys
2017-10-29 19:21   ` [PATCH 05/17] hyper-v: trace vmbus_onopen_result() kys
2017-10-29 19:21   ` [PATCH 06/17] hyper-v: trace vmbus_ongpadl_created() kys
2017-10-29 19:21   ` [PATCH 07/17] hyper-v: trace vmbus_ongpadl_torndown() kys
2017-10-29 19:21   ` [PATCH 08/17] hyper-v: trace vmbus_onversion_response() kys
2017-10-29 19:21   ` [PATCH 09/17] hyper-v: trace vmbus_request_offers() kys
2017-10-29 19:21   ` [PATCH 10/17] hyper-v: trace vmbus_open() kys
2017-10-29 20:59     ` Greg KH
2017-10-30  8:16       ` Vitaly Kuznetsov
2017-10-30  8:45         ` Greg KH
2017-10-30 10:07           ` Vitaly Kuznetsov
2017-10-30 10:32             ` Greg KH
2017-10-30 14:31               ` Steven Rostedt
2017-10-31 12:48                 ` Greg KH
2017-10-31 13:10                   ` Steven Rostedt [this message]
2017-11-01 17:43                     ` KY Srinivasan
2017-11-04 11:05                       ` Greg KH
2017-11-04 15:09                         ` KY Srinivasan
2017-10-31 17:41                   ` Stephen Hemminger
2017-10-29 19:21   ` [PATCH 11/17] hyper-v: trace vmbus_close_internal() kys
2017-10-29 19:21   ` [PATCH 12/17] hyper-v: trace vmbus_establish_gpadl() kys
2017-10-29 19:21   ` [PATCH 13/17] hyper-v: trace vmbus_teardown_gpadl() kys
2017-10-29 19:21   ` [PATCH 14/17] hyper-v: trace vmbus_negotiate_version() kys
2017-10-29 19:21   ` [PATCH 15/17] hyper-v: trace vmbus_release_relid() kys
2017-10-29 19:21   ` [PATCH 16/17] hyper-v: trace vmbus_send_tl_connect_request() kys
2017-10-29 19:21   ` [PATCH 17/17] hyper-v: trace channel events kys

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