Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755415AbZCBSwd (ORCPT ); Mon, 2 Mar 2009 13:52:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751873AbZCBSwY (ORCPT ); Mon, 2 Mar 2009 13:52:24 -0500 Received: from mail.impinj.com ([206.169.229.170]:47182 "EHLO earth.impinj.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751577AbZCBSwX (ORCPT ); Mon, 2 Mar 2009 13:52:23 -0500 X-Greylist: delayed 415 seconds by postgrey-1.27 at vger.kernel.org; Mon, 02 Mar 2009 13:52:23 EST From: Vadim Lobanov To: Linus Torvalds Subject: Re: [RFC][PATCH] irq: remove IRQF_DISABLED Date: Mon, 2 Mar 2009 10:45:20 -0800 User-Agent: KMail/1.11.0 (Linux/2.6.27.15-170.2.24.fc10.x86_64; KDE/4.2.0; x86_64; ; ) Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , lkml , "linux-arch" , Andrew Morton References: <1235996477.5330.174.camel@laptop> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200903021045.20723.vlobanov@speakeasy.net> X-OriginalArrivalTime: 02 Mar 2009 18:45:25.0977 (UTC) FILETIME=[0D0EA490:01C99B67] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1190 Lines: 30 On Monday 02 March 2009 09:11:54 Linus Torvalds wrote: > The thing is, with PIO, a 512-byte disk read ends up doing 256 16-bit word > reads from the controller, each potentially up to 600ns long (PIO0 > timings). That's 150ms - for a single sector! Out of curiosity, the peanut gallery wishes to ask: Is the above supposed to be 600us (*1000), or 150us (/1000)? Probably the latter. > For example, Mode2 timings are probably still something we should consider > realistic, and that's 240ns per word - a single sector now takes ~60ms to > read off the disk. Same factor of 1000 question here. > And we don't do single sectors. Most transfers will be 8 sectors (4k > contiguos read). So now that 60ms is 480ms per such IDE interrupt. And > even with the _good_ timings, we're certainly looking at a reduction of > that to about half. > > Imagine what happens when we have interrupts disabled for half a second at > a time. -- Vadim Lobanov -- 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/