From: Chris Friesen <cfriesen@nortelnetworks.com>
To: Mark Mielke <mark@mark.mielke.cc>
Cc: Martijn Sipkema <martijn@entmoot.nl>,
Adam Heath <doogie@debian.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: UDP recvmsg blocks after select(), 2.6 bug?
Date: Thu, 07 Oct 2004 11:18:25 -0600 [thread overview]
Message-ID: <41657A61.6030601@nortelnetworks.com> (raw)
In-Reply-To: <20041007160914.GB26784@mark.mielke.cc>
Mark Mielke wrote:
> Isn't it more expensive to allow the
> application to be woken up, and poll using read(), than to just do a
> quick check in the kernel and not tell the application there is data,
> when there really isn't?
The issue is caching.
We have to do a pass over the data to copy it to userspace. If we do the
checksum verification then, it's basically free since its already in the cache.
If we do it at select() time, we end up having to do two passes over every
packet, one to verify the checksum, and one to pass it to userspace.
I agree with you though, it'd be nice to have select() change behaviour based on
whether the socket is blocking or not.
Chris
next prev parent reply other threads:[~2004-10-07 17:23 UTC|newest]
Thread overview: 191+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-06 14:52 UDP recvmsg blocks after select(), 2.6 bug? Joris van Rantwijk
2004-10-06 15:01 ` David S. Miller
2004-10-06 15:13 ` Chris Friesen
2004-10-06 15:15 ` Richard B. Johnson
2004-10-06 15:21 ` David S. Miller
2004-10-06 15:29 ` Richard B. Johnson
2004-10-06 15:42 ` David S. Miller
2004-10-06 15:57 ` Chris Friesen
2004-10-06 15:44 ` Lars Marowsky-Bree
2004-10-07 1:16 ` Paul Jakma
2004-10-07 7:10 ` Chris Friesen
2004-10-07 11:53 ` Paul Jakma
2004-10-07 13:32 ` Martijn Sipkema
2004-10-07 12:53 ` Paul Jakma
2004-10-07 13:12 ` Richard B. Johnson
2004-10-07 14:07 ` Martijn Sipkema
2004-10-07 13:19 ` Paul Jakma
2004-10-07 13:36 ` Paul Jakma
2004-10-07 15:01 ` Jean-Sebastien Trottier
2004-10-07 16:20 ` Chris Friesen
2004-10-07 18:20 ` Hua Zhong
2004-10-07 18:33 ` Chris Friesen
2004-10-07 22:41 ` Martijn Sipkema
2004-10-07 21:49 ` Chris Friesen
2004-10-07 22:00 ` David S. Miller
2004-10-07 22:24 ` Chris Friesen
2004-10-07 22:26 ` David S. Miller
2004-10-07 22:39 ` Chris Friesen
2004-10-07 22:42 ` David S. Miller
2004-10-07 23:27 ` Chris Friesen
2004-10-08 0:04 ` Ben Greear
2004-10-08 2:51 ` Mark Mielke
2004-10-08 3:39 ` David S. Miller
2004-10-08 3:48 ` Mark Mielke
2004-10-08 3:59 ` David S. Miller
2004-10-07 23:19 ` Martijn Sipkema
2004-10-07 22:24 ` David S. Miller
2004-10-07 22:33 ` Alan Curry
2004-10-07 22:42 ` Mark Mielke
2004-10-07 22:47 ` David S. Miller
2004-10-07 23:00 ` Mark Mielke
2004-10-07 23:07 ` David S. Miller
2004-10-08 6:10 ` Theodore Ts'o
2004-10-08 15:20 ` Mark Mielke
2004-10-08 0:37 ` Lee Revell
2004-10-07 22:46 ` Hua Zhong
2004-10-07 22:48 ` David S. Miller
2004-10-07 23:17 ` Martijn Sipkema
2004-10-07 13:45 ` Alan Cox
2004-10-07 16:32 ` Martijn Sipkema
2004-10-07 14:50 ` Alan Cox
2004-10-07 21:58 ` mmap specification - was: ... select specification Andries Brouwer
2004-10-07 22:17 ` Chris Wedgwood
2004-10-07 22:34 ` Andries Brouwer
2004-10-07 22:32 ` Kyle Moffett
2004-10-07 22:46 ` Andries Brouwer
2004-10-07 23:30 ` Kyle Moffett
2004-10-08 9:19 ` Andries Brouwer
2004-10-09 21:10 ` Martijn Sipkema
2004-10-07 13:48 ` UDP recvmsg blocks after select(), 2.6 bug? Alan Cox
2004-10-07 14:57 ` Richard B. Johnson
2004-10-07 15:18 ` Adam Heath
2004-10-07 16:39 ` Martijn Sipkema
2004-10-07 16:09 ` Mark Mielke
2004-10-07 17:18 ` Chris Friesen [this message]
2004-10-06 15:31 ` Chris Friesen
2004-10-06 15:41 ` David S. Miller
2004-10-06 16:07 ` Richard B. Johnson
2004-10-06 16:57 ` Neil Horman
2004-10-06 15:59 ` Paul Jackson
2004-10-06 16:35 ` Martijn Sipkema
2004-10-06 15:30 ` Chris Friesen
2004-10-06 15:09 ` Richard B. Johnson
2004-10-06 15:18 ` bert hubert
2004-10-06 16:41 ` Alan Cox
2004-10-06 18:04 ` Joris van Rantwijk
2004-10-06 19:30 ` Andries Brouwer
2004-10-06 19:23 ` Alan Cox
2004-10-06 22:08 ` Martijn Sipkema
2004-10-06 20:25 ` Alan Cox
2004-10-06 22:15 ` Andries Brouwer
2004-10-06 22:32 ` David S. Miller
2004-10-06 23:25 ` YOSHIFUJI Hideaki / 吉藤英明
2004-10-06 23:11 ` Willy Tarreau
2004-10-06 19:43 ` Hua Zhong
2004-10-06 19:54 ` Chris Friesen
2004-10-06 19:59 ` Hua Zhong
2004-10-06 20:10 ` Chris Friesen
2004-10-06 21:45 ` Martijn Sipkema
2004-10-06 23:35 ` David S. Miller
2004-10-06 20:06 ` David S. Miller
2004-10-06 20:18 ` Chris Friesen
2004-10-06 20:26 ` Hua Zhong
2004-10-06 20:38 ` Andries Brouwer
2004-10-06 20:58 ` Joris van Rantwijk
2004-10-06 22:29 ` David S. Miller
2004-10-07 16:08 ` Adrian Phillips
2004-10-06 20:06 ` Olivier Galibert
2004-10-06 23:35 ` David S. Miller
2004-10-07 0:19 ` Olivier Galibert
2004-10-07 0:29 ` David S. Miller
2004-10-07 10:56 ` Martijn Sipkema
2004-10-08 6:41 ` Willy Tarreau
2004-10-08 15:27 ` Mark Mielke
2004-10-15 22:42 ` Robert White
2004-10-15 23:33 ` David Schwartz
2004-10-16 0:59 ` Chris Friesen
2004-10-16 2:35 ` Mark Mielke
2004-10-16 4:23 ` David Schwartz
2004-10-16 4:35 ` Mark Mielke
2004-10-16 4:58 ` David Schwartz
2004-10-16 6:25 ` Mark Mielke
2004-10-16 21:44 ` Roland Kuhn
2004-10-17 0:06 ` Mark Mielke
2004-10-17 0:30 ` David Schwartz
2004-10-17 14:47 ` Mark Mielke
2004-10-17 0:28 ` David Schwartz
2004-10-17 13:35 ` Lars Marowsky-Bree
2004-10-17 14:17 ` Buddy Lucas
2004-10-17 15:05 ` Mark Mielke
2004-10-17 15:40 ` Buddy Lucas
2004-10-17 16:13 ` Lee Revell
2004-10-17 17:35 ` Jesper Juhl
2004-10-17 18:04 ` Buddy Lucas
2004-10-17 18:06 ` Lars Marowsky-Bree
2004-10-17 18:21 ` Buddy Lucas
2004-10-17 20:04 ` Martijn Sipkema
2004-10-17 20:08 ` Lars Marowsky-Bree
2004-10-17 17:35 ` Martijn Sipkema
2004-10-17 17:33 ` Buddy Lucas
2004-10-17 19:58 ` Martijn Sipkema
2004-10-17 19:33 ` Buddy Lucas
2004-10-17 20:11 ` Lars Marowsky-Bree
2004-10-17 20:25 ` Buddy Lucas
2004-10-17 20:42 ` Martijn Sipkema
2004-10-17 20:02 ` Buddy Lucas
2004-10-17 18:53 ` David Schwartz
2004-10-17 19:26 ` Hua Zhong
2004-10-17 20:32 ` Martijn Sipkema
2004-10-17 19:21 ` Hua Zhong
2004-10-17 17:22 ` Lars Marowsky-Bree
2004-10-17 17:54 ` Buddy Lucas
2004-10-17 18:05 ` Lars Marowsky-Bree
2004-10-17 18:06 ` Mark Mielke
2004-10-20 21:31 ` H. Peter Anvin
2004-10-20 21:58 ` Chris Friesen
2004-10-20 22:00 ` H. Peter Anvin
2004-10-20 22:12 ` Chris Friesen
2004-10-20 23:16 ` David Schwartz
2004-10-21 1:03 ` Chris Friesen
2004-10-21 1:38 ` David Schwartz
2004-10-21 3:01 ` Michael Clark
2004-10-21 3:52 ` Michael Clark
2004-10-21 4:10 ` H. Peter Anvin
2004-10-21 5:06 ` Chris Friesen
2004-10-21 5:11 ` H. Peter Anvin
2004-10-21 5:50 ` Chris Friesen
2004-10-21 5:58 ` H. Peter Anvin
2004-10-21 15:18 ` Chris Friesen
2004-10-21 6:14 ` Michael Clark
2004-10-17 14:52 ` Mark Mielke
2004-10-16 18:25 ` Andries Brouwer
2004-10-17 0:28 ` David Schwartz
2004-10-17 12:22 ` Andries Brouwer
2004-10-16 10:24 ` Willy Tarreau
2004-10-16 13:21 ` Mark Mielke
2004-10-18 22:25 ` Robert White
2004-10-06 20:41 ` Neil Horman
2004-10-06 22:27 ` Chris Friesen
2004-10-06 23:32 ` Neil Horman
2004-10-06 23:36 ` David S. Miller
2004-10-07 19:31 ` David Schwartz
2004-10-07 22:36 ` Martijn Sipkema
2004-10-08 0:19 ` David Schwartz
2004-10-09 19:21 ` Martijn Sipkema
2004-10-09 18:28 ` David Schwartz
2004-10-09 18:49 ` Mark Mielke
2004-10-09 21:00 ` Martijn Sipkema
2004-10-09 22:59 ` Mark Mielke
-- strict thread matches above, loose matches on Subject: below --
2004-10-06 15:30 Dan Kegel
2004-10-07 4:50 Dan Kegel
2004-10-07 8:04 ` bert hubert
2004-10-07 8:28 ` Adam Heath
2004-10-07 10:38 ` Martijn Sipkema
2004-10-07 10:07 ` Adam Heath
2004-10-07 11:29 ` Martijn Sipkema
2004-10-07 18:16 linux
2004-10-09 12:07 ` Colin Phipps
[not found] <fa.haprsoi.8k8kbk@ifi.uio.no>
[not found] ` <fa.isqjio8.ok2coo@ifi.uio.no>
2004-10-09 13:24 ` Bodo Eggert
2004-10-19 1:21 John Pearson
2004-10-19 13:50 ` Colin Phipps
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