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Date: Wed, 02 Jan 2002 19:26:15 +0100
From: Edgar Toernig <froese@gmx.de>
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To: Michal Moskal <malekith@pld.org.pl>
CC: linux-kernel@vger.kernel.org
Subject: Re: strange TCP stack behiviour with write()es in pieces
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Michal Moskal wrote:
> 
> So, it occurs in programs doing packet communication over TCP, when
> peer waits for a packet to send an answer. If they send data with two
> write() calls (for example to write packet header and packet data),
> the performance dramaticly decrases (down to exactly 100 (2.2.19)
> or 25 (2.4.[57]) packet exchanges per second on x86, from several
> thousands. 100 seems to be related to HZ variable, see also AXP results,
> where HZ is 10 times bigger).

Try disabling the nagle algorithm:

        int i = 1;
        if (setsockopt(fd, SOL_TCP, TCP_NODELAY, &i, sizeof(i)) == -1)
            perror("TCP_NODELAY");

Ciao, ET.
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