Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753059AbYJ0BS1 (ORCPT ); Sun, 26 Oct 2008 21:18:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750740AbYJ0BSS (ORCPT ); Sun, 26 Oct 2008 21:18:18 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:43045 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710AbYJ0BSS (ORCPT ); Sun, 26 Oct 2008 21:18:18 -0400 X-AuthUser: davidel@xmailserver.org Date: Sun, 26 Oct 2008 18:18:00 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Paul P cc: Linux Kernel Mailing List Subject: Re: unexpected extra pollout events from epoll In-Reply-To: <107660.83879.qm@web56306.mail.re3.yahoo.com> Message-ID: References: <107660.83879.qm@web56306.mail.re3.yahoo.com> X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1700 Lines: 54 On Sun, 26 Oct 2008, Paul P wrote: > > You do that by writing data until it's finished, or you > > get EAGAIN. If you > > get EAGAIN, you listen for EPOLLOUT. > > Reading is same, but you'd wait for EPOLLIN. > > I've got a few questions about this approach. The most logical > way to do this seems to be: > > 1) Leave the epoll_wait with the EPOLLIN|EPOLLOUT event flags and > use epoll_ctl to switch the interest mask for each fd between EPOLLIN > and EPOLLOUT on a per fd basis. Which version of epoll do you have? The epoll_wait() function does not accept an event mask (like you write above, EPOLLIN|EPOLLOUT). It never had. But yes, you'd switch interest with epoll_ctl(). > 2) When I'm ready to write, I do a write and if it does not fully > write and I get the EAGAIN flag, I switch the fd with epoll_ctl(fd,MOD,EPOLLOUT). As optimization, if the EPOLLOUT bit is already set, you don't need to keep calling epoll_ctl(fd,MOD,EPOLLOUT). > However, I get strange behavior when I tried adding fd's with only the > EPOLLIN interest mask. If I use epoll_wait with both the EPOLLIN and > EPOLLOUT interest mask, but add fd's with only the EPOLLIN interest mask, > I still seem to get EPOLLOUT events on the fd. Again, how the heck do you "use epoll_wait with both the EPOLLIN and EPOLLOUT"?!? There is not such a thing. > So, I'm a little confused. >From the wording above, that doesn't seem like a wrong guess. - Davide -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/