Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 15 Jul 2002 04:56:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 15 Jul 2002 04:56:45 -0400 Received: from CPE00608c86a77d.cpe.net.cable.rogers.com ([24.157.76.7]:33540 "EHLO mielke.cc") by vger.kernel.org with ESMTP id ; Mon, 15 Jul 2002 04:56:44 -0400 Date: Mon, 15 Jul 2002 04:58:05 -0400 (EDT) From: Dave Mielke To: Linus Torvalds cc: "Linux Kernel (mailing list)" Subject: Re: HZ, preferably as small as possible In-Reply-To: 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 Content-Length: 1828 Lines: 32 [quoted lines by Linus Torvalds on July 15, 2002, at 05:15] >The fact that the kernel internally counts at some different rate should >be _totally_ invisible to user programs (except they get better latency >for stuff like select() and other timeouts). I believe your position to be right on. May I ask, however, about a quandry which we have in BRLTTY? We generate short "tunes" via the PC speaker in order to give a blind user audible clues regarding certain events. To do this, we need rather precise control over how long each note is on. Due to the current lack of granularity, we need to do some rather long busy loops. This has worked out okay, but it'd of course be much better if we could rely on the kernel to do it, especially on a busy system, if its granularity is good enough. My quandry is that while I don't believe that user land should know what granularity the kernel is using, I'd still like to know if we should busy loop or let the kernel do it depending on whether or not the kernel's granularity is good enough for our needs. It'd be nice to have a way, therefore, to query two values at run time, i.e. the granularity that services like select can offer and the maximum amount of time that nanosleep will do a very accurate short wait, although I suppose that these abilities could be abused by some. -- Dave Mielke | 2213 Fox Crescent | I believe that the Bible is the Phone: 1-613-726-0014 | Ottawa, Ontario | Word of God. Please contact me EMail: dave@mielke.cc | Canada K2A 1H7 | if you're concerned about Hell. http://familyradio.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/