From: John <linux.kernel@free.fr>
To: linux-kernel@vger.kernel.org
Cc: johnstul@us.ibm.com, mingo@elte.hu, zippel@linux-m68k.org,
tglx@timesys.com, linux.kernel@free.fr,
akpm@linux-foundation.org
Subject: CLOCK_MONOTONIC datagram timestamps by the kernel
Date: Sun, 25 Feb 2007 22:29:48 +0100 [thread overview]
Message-ID: <45E1FFCC.50201@free.fr> (raw)
Hello,
It is possible to ask Linux to timestamp incoming datagrams when they
are received, then to retrieve this timestamp with an ioctl command or
a recvmsg call (which would save one round trip to kernel space).
SIOCGSTAMP
Return a struct timeval with the receive timestamp of the last
packet passed to the user. This is useful for accurate round trip time
measurements. See setitimer(2) for a description of struct timeval.
As far as I understand, this timestamp is given by the CLOCK_REALTIME
clock. I would like to get the timestamp given by a different clock: the
CLOCK_MONOTONIC clock.
In other words, I would like the kernel to do the equivalent of
struct timespec spec;
clock_gettime(CLOCK_MONOTONIC, &spec)
for each datagram the system receives, as soon as it is received.
Is there a way to achieve that?
Is there a different ioctl perhaps? (I don't think so.)
Regards.
next reply other threads:[~2007-02-25 21:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-25 21:29 John [this message]
2007-02-26 10:26 ` CLOCK_MONOTONIC datagram timestamps by the kernel John
2007-02-26 12:20 ` Andi Kleen
2007-02-26 14:17 ` John
2007-02-28 11:23 ` John
2007-02-28 10:18 John
2007-02-28 13:37 ` John
2007-02-28 13:55 ` Eric Dumazet
2007-02-28 14:23 ` John
2007-02-28 14:55 ` Eric Dumazet
2007-02-28 16:07 ` John
2007-03-01 10:03 ` Evgeniy Polyakov
2007-03-01 11:30 ` Eric Dumazet
2007-03-01 15:54 ` Stephen Hemminger
2007-03-01 16:13 ` Eric Dumazet
2007-03-01 18:53 ` Stephen Hemminger
2007-03-01 23:14 ` Eric Dumazet
2007-03-01 23:34 ` Stephen Hemminger
2007-03-02 0:56 ` Eric Dumazet
2007-03-02 9:26 ` John
2007-03-02 10:11 ` Eric Dumazet
2007-02-28 18:22 ` Stephen Hemminger
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