From owner-freebsd-arch@FreeBSD.ORG  Wed May 28 22:22:57 2003
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Date: Thu, 29 May 2003 09:22:54 +0400 (MSD)
From: Igor Sysoev <is@rambler-co.ru>
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To: Terry Lambert <tlambert2@mindspring.com>
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cc: arch@freebsd.org
Subject: Re: sendfile(2) SF_NOPUSH flag proposal
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On Wed, 28 May 2003, Terry Lambert wrote:

> Bill Fenner wrote:
> > Why not set PRUS_MORETOCOME on all but the final pru_send() call?
> 
> If the file is larger than `sysctl net.inet.tcp.sendspace`, then
> this code in do_sendfile():
> 
>                 if (sbspace(&so->so_snd) < so->so_snd.sb_lowat) {
>                         if (so->so_state & SS_NBIO) {
>                                 m_freem(m);
>                                 sbunlock(&so->so_snd);
>                                 splx(s);
>                                 error = EAGAIN;
>                                 goto done;
>                         }
>                         error = sbwait(&so->so_snd);
> 
> will result in you sleeping with PRUS_MORETOCOME set, but with
> no more being sent because the send buffer doesn't get emptied,
> as it's waiting for more data to send.

But as I understand PRUS_MORETOCOME is not set if socket is non-blocking.


Igor Sysoev
http://sysoev.ru/en/