Date: Wed, 28 May 2003 23:56:24 +0400 (MSD) From: Igor Sysoev <is@rambler-co.ru> To: Bill Fenner <fenner@research.att.com> Cc: arch@freebsd.org Subject: Re: sendfile(2) SF_NOPUSH flag proposal Message-ID: <Pine.BSF.4.21.0305282355390.51293-100000@is> In-Reply-To: <200305281755.h4SHtbu05504@windsor.research.att.com>
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On Wed, 28 May 2003, Bill Fenner wrote:
> Why not set PRUS_MORETOCOME on all but the final pru_send() call?
I think it's a good solution. We can
1) use TF_NOPUSH to coalesce the header and the first file part
or the last file part and the trailer as Matthew Dillon suggested;
2) use the same TF_NOPUSH to postpone the sending partial packet while
a reading file page from the disk;
3) and use PRUS_MORETOCOME to avoid partial packet after EAGAIN
on non-blocking socket.
----------
sendfile()
{
saved = tp->t_flags & TF_NOPUSH;
if (header) {
writev(header);
}
if (file) {
send file pages with PRUS_MORETOCOME
}
if (trailer) {
writev(trailer);
}
done:
if (sendfile completed) {
tp->t_flags &= ~TF_MORETOCOME;
}
tp->t_flags |= saved;
if (saved & TF_NOPUSH) {
tcp_output(tp);
}
}
----------
As I understand TF_MORETOCOME should postpone the sending the partially
filled packet after sendfile will return EAGAIN.
Igor Sysoev
http://sysoev.ru/en/
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