From: Andi Kleen <ak@suse.de>
To: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] zerocopy NFS updated
Date: 10 Apr 2002 21:32:22 +0200 [thread overview]
Message-ID: <p73662zpcxl.fsf@oldwotan.suse.de> (raw)
In-Reply-To: <20020410.190550.83626375.taka@valinux.co.jp.suse.lists.linux.kernel>
Hirokazu Takahashi <taka@valinux.co.jp> writes:
> But I wonder about sendpage. I guess HW IP checksum for outgoing
> pages might be miscalculated as VFS can update them anytime.
> New feature like COW pagecache should be added to VM and they
> should be duplicated in this case.
For hw checksums it should not be a problem. NICs usually load
the packet into their packet fifo and compute the checksum on the fly
and then patch it into the header in the fifo before sending it out. A
NIC that would do slow PCI bus mastering twice just to compute the checksum
would be very dumb and I doubt they exist (if yes I bet it would be
faster to do software checksumming on them). When the NIC only
accesses the memory once there is no race window.
-Andi
next parent reply other threads:[~2002-04-10 19:32 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20020410.190550.83626375.taka@valinux.co.jp.suse.lists.linux.kernel>
2002-04-10 19:32 ` Andi Kleen [this message]
2002-04-11 2:30 ` [PATCH] zerocopy NFS updated David S. Miller
2002-04-11 6:46 ` Hirokazu Takahashi
2002-04-11 6:48 ` David S. Miller
2002-04-11 7:41 ` Hirokazu Takahashi
2002-04-11 7:52 ` David S. Miller
2002-04-11 11:38 ` Hirokazu Takahashi
2002-04-11 11:36 ` David S. Miller
2002-04-11 18:00 ` Denis Vlasenko
2002-04-11 13:16 ` Andi Kleen
2002-04-11 17:36 ` Benjamin LaHaise
2002-04-16 0:17 ` Mike Fedyk
2002-04-16 15:37 ` Oliver Xymoron
2002-04-11 17:33 ` Benjamin LaHaise
2002-04-12 8:10 ` Hirokazu Takahashi
2002-04-12 12:30 ` Hirokazu Takahashi
2002-04-12 12:35 ` Andi Kleen
2002-04-12 21:22 ` Jamie Lokier
2002-04-12 21:31 ` David S. Miller
2002-04-13 0:21 ` Jamie Lokier
2002-04-13 6:39 ` Andi Kleen
2002-04-13 8:01 ` Hirokazu Takahashi
2002-04-13 19:19 ` Eric W. Biederman
2002-04-13 19:37 ` Andi Kleen
2002-04-13 20:34 ` Eric W. Biederman
2002-04-24 23:11 ` Mike Fedyk
2002-04-25 17:11 ` Andreas Dilger
2002-04-13 18:52 ` Chris Wedgwood
2002-04-14 0:07 ` Keith Owens
2002-04-14 8:19 ` Chris Wedgwood
2002-04-14 8:40 ` Keith Owens
2002-04-12 21:39 ` David S. Miller
2002-04-15 1:30 ` Hirokazu Takahashi
2002-04-15 4:23 ` David S. Miller
2002-04-16 1:03 ` Hirokazu Takahashi
2002-04-16 1:41 ` Jakob Østergaard
2002-04-16 2:20 ` Hirokazu Takahashi
2002-04-18 5:01 ` Hirokazu Takahashi
2002-04-18 7:58 ` Jakob Østergaard
2002-04-18 8:53 ` Trond Myklebust
2002-04-19 3:21 ` Hirokazu Takahashi
2002-04-19 9:18 ` Trond Myklebust
2002-04-20 7:47 ` Hirokazu Takahashi
2002-04-25 12:37 ` Possible bug with UDP and SO_REUSEADDR. Was " Terje Eggestad
2002-04-26 2:43 ` David S. Miller
2002-04-26 7:38 ` Terje Eggestad
2002-04-29 0:41 ` Possible bug with UDP and SO_REUSEADDR David Schwartz
2002-04-29 8:06 ` Terje Eggestad
2002-04-29 8:44 ` David Schwartz
2002-04-29 10:03 ` Terje Eggestad
2002-04-29 10:38 ` David Schwartz
2002-04-29 14:20 ` Terje Eggestad
[not found] ` <200204192128.QAA24592@popmail.austin.ibm.com>
2002-04-20 10:14 ` [PATCH] zerocopy NFS updated Hirokazu Takahashi
2002-04-20 15:49 ` Andrew Theurer
2002-04-10 10:05 Hirokazu Takahashi
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