From: Manfred Spraul <manfred@colorfullife.com>
To: "David S. Miller" <davem@redhat.com>
Cc: wli@holomorphy.com, anton@samba.org, linux-kernel@vger.kernel.org
Subject: Re: 2.5.50-BK + 24 CPUs
Date: Mon, 09 Dec 2002 22:12:58 +0100 [thread overview]
Message-ID: <3DF5075A.2090009@colorfullife.com> (raw)
In-Reply-To: <20021209.121557.17268348.davem@redhat.com>
David S. Miller wrote:
> From: Manfred Spraul <manfred@colorfullife.com>
> Date: Mon, 09 Dec 2002 18:03:10 +0100
>
> Unfortunately zero-copy doesn't help to avoid the schedules:
> Zero copy just avoid the copy to kernel - you still need one schedule
> for each page to be transfered.
>
>The zerocopy patches copied up to 64k (or rather, 16 pages, something
>like that) at once, that's going to lead to 16 times less schedules.
>
>The 64k number was decided arbitrarily (it's what freebsd's pipe code
>uses) and it can be experimented with.
>
>
Only if user space writes in 64 kB chunks - if user space writes 4 kB
chunks, then zerocopy doesn't help much against schedule [depending on
the implementation, it halves the number of schedules].
And page table tricks (COW) tricks are not acceptable.
--
Manfred
next prev parent reply other threads:[~2002-12-09 21:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-08 21:22 2.5.50-BK + 24 CPUs Manfred Spraul
2002-12-08 21:28 ` William Lee Irwin III
2002-12-08 23:22 ` David S. Miller
2002-12-08 23:01 ` William Lee Irwin III
2002-12-09 17:03 ` Manfred Spraul
2002-12-09 20:15 ` David S. Miller
2002-12-09 21:12 ` Manfred Spraul [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-12-08 13:09 Anton Blanchard
2002-12-08 14:49 ` Rik van Riel
2002-12-08 16:45 ` Rik van Riel
2002-12-09 14:08 ` Anton Blanchard
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