From: "Frank Ch. Eigler" <fche@redhat.com>
To: Neil Horman <nhorman@tuxdriver.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>,
"Frank Ch. Eigler" <fche@elastic.org>,
Satoru Moriya <satoru.moriya@hds.com>,
David Miller <davem@davemloft.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"tgraf@infradead.org" <tgraf@infradead.org>,
"stephen.hemminger@vyatta.com" <stephen.hemminger@vyatta.com>,
"eric.dumazet@gmail.com" <eric.dumazet@gmail.com>,
Seiji Aguchi <seiji.aguchi@hds.com>,
fche@sourceware.org, mathieu.desnoyers@polymtl.ca,
rostedt@goodmis.org
Subject: Re: [PATCH v2 0/2] Tracepoint for tcp retransmission
Date: Mon, 6 Feb 2012 10:20:19 -0500 [thread overview]
Message-ID: <20120206152019.GG27935@redhat.com> (raw)
In-Reply-To: <20120206013247.GA5681@neilslaptop.think-freely.org>
Hi, Neil -
On Sun, Feb 05, 2012 at 08:32:47PM -0500, Neil Horman wrote:
> [...]
> > Hey Neil, I though about this more deeply. In my first iteration I
> > had the same answer. But IMHO if you think about this more deeply,
> > I think this is not a scalable approach (implementing in userspace
> > as systemtap scripts compared to implement them in kernelspace
> > (tracepoints). Why? Because at a deep TCP level the API (and thus
> > the context) is not static and the meaning of return values (or
> > arguments) change over time. No matter _where_ it is implemented
> > or coded.
> Yes, this is why I'm suggesting alternatives to the tracepoint.
I believe Hagen's point was that alternatives to tracepoints would
have substantially the same difficulty. At some point in the stack,
you have to standardize/abstract. What you hook up *at that point* is
not too important: tracepoints, or function calls, or expanded perf
machinery all seem to have the same burden.
> [...] If something is needed in the short term for Satoru, I still
> think a privately maintained module that registers a netfilter hook
> to watch outgoing packets for retransmits offers a good solution.
Does this mean that this netfilter hook mechanism is sufficient to
adapt to the current/future diversity of behaviors? Why not make
*that* into a tracepoint then, so perf/stap scripts could get at it in
userspace?
- FChE
next prev parent reply other threads:[~2012-02-06 15:21 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-20 18:07 [PATCH v2 0/2] Tracepoint for tcp retransmission Satoru Moriya
2012-01-20 18:08 ` [PATCH v2 1/2] tcp: refactor tcp_retransmit_skb() for a single return point Satoru Moriya
2012-01-20 18:09 ` [PATCH v2 2/2] tcp: add tracepoint for tcp retransmission Satoru Moriya
2012-01-20 18:50 ` [PATCH v2 0/2] Tracepoint " David Miller
2012-02-03 21:47 ` Satoru Moriya
2012-02-04 4:40 ` Yuchung Cheng
2012-02-06 18:32 ` Satoru Moriya
2012-02-04 14:28 ` Neil Horman
2012-02-04 15:58 ` Hagen Paul Pfeifer
2012-02-04 20:09 ` Neil Horman
2012-02-05 12:53 ` Frank Ch. Eigler
2012-02-05 19:17 ` Neil Horman
2012-02-05 20:04 ` Hagen Paul Pfeifer
2012-02-05 21:48 ` David Miller
2012-02-06 1:32 ` Neil Horman
2012-02-06 15:20 ` Frank Ch. Eigler [this message]
2012-02-06 15:24 ` Eric Dumazet
2012-02-06 15:38 ` Neil Horman
2012-02-06 15:53 ` Neil Horman
2012-02-06 16:18 ` Steven Rostedt
2012-02-06 17:02 ` Eric Dumazet
2012-02-06 17:18 ` Steven Rostedt
2012-02-06 16:21 ` Frank Ch. Eigler
2012-02-06 18:21 ` Satoru Moriya
2012-01-25 13:27 ` Hagen Paul Pfeifer
2012-01-25 14:44 ` Eric Dumazet
2012-01-26 18:51 ` David Miller
2012-02-03 20:31 ` Satoru Moriya
2012-02-03 20:43 ` Satoru Moriya
2012-02-03 20:55 ` Hagen Paul Pfeifer
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