Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 8 Feb 2001 09:00:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 8 Feb 2001 09:00:41 -0500 Received: from nat-pool.corp.redhat.com ([199.183.24.200]:53991 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id ; Thu, 8 Feb 2001 09:00:33 -0500 Date: Thu, 8 Feb 2001 08:57:33 -0500 (EST) From: Ben LaHaise To: Pavel Machek cc: Linus Torvalds , Marcelo Tosatti , Jens Axboe , Manfred Spraul , Ingo Molnar , "Stephen C. Tweedie" , Alan Cox , Steve Lord , Linux Kernel List , , Ingo Molnar Subject: Re: select() returning busy for regular files [was Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait] In-Reply-To: <20010208001735.C189@bug.ucw.cz> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 8 Feb 2001, Pavel Machek wrote: > Hi! > > > > Its arguing against making a smart application block on the disk while its > > > able to use the CPU for other work. > > > > There are currently no other alternatives in user space. You'd have to > > create whole new interfaces for aio_read/write, and ways for the kernel to > > inform user space that "now you can re-try submitting your IO". > > Why is current select() interface not good enough? Think of random disk io scattered across the disk. Think about aio_write providing a means to perform zero copy io without needing to resort to playing mm tricks write protecting pages in the user's page tables. It's also a means for dealing efficiently with thousands of outstanding requests for network io. Using a select based interface is going to be an ugly kludge that still has all the overhead of select/poll. -ben - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/