Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756767AbZGGHpj (ORCPT ); Tue, 7 Jul 2009 03:45:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753895AbZGGHpb (ORCPT ); Tue, 7 Jul 2009 03:45:31 -0400 Received: from mail-qy0-f193.google.com ([209.85.221.193]:33748 "EHLO mail-qy0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753436AbZGGHpb convert rfc822-to-8bit (ORCPT ); Tue, 7 Jul 2009 03:45:31 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=HY2mNIucomykXiWmIr/VnAr5uTGnuUBActmRPA9XnlD4R05ajBwzwUCdpGgVCtIzVp ubUKVW3JLfUBegBxdWUOJOBuqHmg3guXeLhHHD9PakpMPqO0TK+KRuIpr2i7np4htyar VDofZUkdDoCj7A3xa1LiD0m3dcD8+Gacr+6NQ= MIME-Version: 1.0 In-Reply-To: <200907070643.56394.vda.linux@googlemail.com> References: <20090703015554.GB5880@cr0.nay.redhat.com> <412e6f7f0907030259m5556ee2fobbb58d377bce4d17@mail.gmail.com> <4A4DDD54.9030206@free.fr> <200907070643.56394.vda.linux@googlemail.com> Date: Tue, 7 Jul 2009 15:45:34 +0800 Message-ID: <412e6f7f0907070045o6a17fb10x557108ffde0da11@mail.gmail.com> Subject: Re: PROPOSAL: extend pipe() to support NULL argument. From: Changli Gao To: Denys Vlasenko Cc: Albert ARIBAUD , Linux Kernel Mailing List , Amerigo Wang , Linus Torvalds Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1020 Lines: 31 On Tue, Jul 7, 2009 at 12:43 PM, Denys Vlasenko wrote: > On Friday 03 July 2009 12:28, Albert ARIBAUD wrote: > > As I understand it, the proposal is to make pipe(NULL) return a fd, > which can be read from and written to. Whatever you write > is remembered, and can be retrieved by reads later. > > standard pipe(two_fds) returns two fds. One is only used for writes. > Another is only used for reads. Which may be wasteful in some > situations (like, if you have thousands of pipes). > > There is no trick I know of which may be used to "combine" > these two fds into one, close second one and thus save one fd table slot. > Right! mkfifo(name); open(name, O_RDWR); unlink(name); Is it a trick? -- Regards， Changli Gao(xiaosuo@gmail.com) -- 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/