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Re: Is sendfile all that sexy?

To: jamal <hadi@xxxxxxxxxx>
Subject: Re: Is sendfile all that sexy?
From: Ingo Molnar <mingo@xxxxxxx>
Date: Sun, 14 Jan 2001 20:09:54 +0100 (CET)
Cc: <linux-kernel@xxxxxxxxxxxxxxx>, <netdev@xxxxxxxxxxx>
In-reply-to: <Pine.GSO.4.30.0101141356050.12354-100000@shell.cyberus.ca>
Reply-to: <mingo@xxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
On Sun, 14 Jan 2001, jamal wrote:

> Already doing the single file, single process. [...]

in this case there could still be valid performance differences, as
copying from user-space is cheaper than copying from the pagecache. To
rule out SMP interactions, you could try a UP-IOAPIC kernel on that box.

(I'm also curious what kind of numbers you'll get with the zerocopy
patch.)

> However, i do run by time which means i could read the file from the
> begining(offset 0) to the end then re-do it for as many times as
> 15secs would allow. Does this affect it? [...]

no, in the case of a single thread this should have minimum impact. But
i'd suggest to increase the /proc/sys/net/tcp*mem* values (to 1MB or
more).

        Ingo


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