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Date: Tue, 6 Feb 2001 10:30:58 +0100 (CET)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: <mingo@elte.hu>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Roman Zippel <zippel@fh-brandenburg.de>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>,
        "Stephen C. Tweedie" <sct@redhat.com>,
        Manfred Spraul <manfred@colorfullife.com>,
        Christoph Hellwig <hch@caldera.de>, Steve Lord <lord@sgi.com>,
        <linux-kernel@vger.kernel.org>,
        <kiobuf-io-devel@lists.sourceforge.net>
Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait
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On Mon, 5 Feb 2001, Linus Torvalds wrote:

> [...] But talk to Davem and ank about why they wanted vectors.

one issue is allocation overhead. The fragment array is a natural and
constant-size part of an skb, thus we get all the control structures in
place while allocating a structure that we have to allocate anyway.

another issue is that certain cards have (or can have) SG-limits, so we
have to be prepared to have a 'limited' array of fragments anyway, and
have to be prepared to split/refragment packets. Whether there is a global
MAX_SKB_FRAGS limit or not makes no difference.

	Ingo

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