From: Hagen Paul Pfeifer <hagen@jauu.net>
To: Satoru Moriya <satoru.moriya@hds.com>
Cc: <netdev@vger.kernel.org>, <davem@davemloft.net>,
<nhorman@tuxdriver.com>, <tgraf@infradead.org>,
Stephen Hemminger <stephen.hemminger@vyatta.com>,
<eric.dumazet@gmail.com>, Seiji Aguchi <seiji.aguchi@hds.com>
Subject: Re: [PATCH v2 0/2] Tracepoint for tcp retransmission
Date: Wed, 25 Jan 2012 14:27:59 +0100 [thread overview]
Message-ID: <02e98f84ee62073e1bf92338f6744fde@localhost> (raw)
In-Reply-To: <65795E11DBF1E645A09CEC7EAEE94B9CB728DD67@USINDEVS02.corp.hds.com>
On Fri, 20 Jan 2012 13:07:02 -0500, Satoru Moriya wrote:
> With this tracepoint, we can know whether the packet drop occurred
> in the server (moreover in the kernel) or not. For example, if we
> finds that retransmission failed (tcp_retransmit_skb() returned
> negative value), it means the kernel may have some troubles at
> that time and we can drill down on issues in the kernel based on
> trace data. OTOH, if retransmission succeeded, packet is dropped
> outside the kernel/server.
This is an equivalent replacement and by means not so intrusive:
probe kernel.function("tcp_retransmit_skb").return {
printf("%s -> %d", probefunc(), retval())
}
and print inet_sk($sk)->inet_num for
kernel.function("tcp_retransmit_skb").
It is crazy to add everywhere new tracepoints. Systemtap is far from being
perfect and as smooth as dtrace. But this is an example where systemtap is
suitable and should be used.
Satoru, you wrote systemtap is not suitable - why?
Hagen
next prev parent reply other threads:[~2012-01-25 13:28 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
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 [this message]
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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