From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754174AbYBRNq5 (ORCPT ); Mon, 18 Feb 2008 08:46:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751573AbYBRNqt (ORCPT ); Mon, 18 Feb 2008 08:46:49 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:34908 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751246AbYBRNqs (ORCPT ); Mon, 18 Feb 2008 08:46:48 -0500 Date: Mon, 18 Feb 2008 14:38:53 +0100 From: Pavel Machek To: kernel list , jikos@suse.cz, Thomas Gleixner , Ingo Molnar Cc: "Rafael J. Wysocki" , Andrew Morton Subject: tsc breaks atkbd suspend Message-ID: <20080218133852.GA1573@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! I'm trying to use the "sleepy test" here, unfortunately it locks for 10-or-so seconds. Problem is in wait_event_timeout: timeouts take about 100x as long as they should. Code in drivers/input/serio/libps2.c: + printk("ps2_command waiting event: %d\n", timeout); timeout = wait_event_timeout(ps2dev->wait, !(ps2dev->flags & PS2_FLAG_CMD1),timeout); if (ps2dev->cmdcnt && timeout > 0) { + printk("wait_event returned: %d\n", timeout); timeout = ps2_adjust_timeout(ps2dev, command, timeout); + + printk("ps2_command adjust timeout: %d\n", timeout); wait_event_timeout(ps2dev->wait, !(ps2dev->flags & PS2_FLAG_CMD), timeout); } + printk("ps2_command receiving\n"); ...and I get hang after "ps2_command adjust timeout" for 10 seconds, while it should wait 10msec or so. I even tried adding: + printk("ps2: testing timeouts\n"); + timeout = wait_event_timeout(ps2dev->wait, 0, 10); + printk("ps2: testing timeouts\n"); + timeout = wait_event_timeout(ps2dev->wait, 0, 10); + printk("ps2: testing timeouts\n"); + timeout = wait_event_timeout(ps2dev->wait, 0, 10); + printk("ps2: testing timeouts\n"); + timeout = wait_event_timeout(ps2dev->wait, 0, 10); + printk("ps2: testing timeouts\n"); + timeout = wait_event_timeout(ps2dev->wait, 0, 10); + printk("ps2: timeouts ok?\n"); before that, and yes, those wait too long, too... (but only during suspend, they work ok during boot). nohz=off fixes that. notsc fixes that, too... On my system (thinkpad x60 in UP mode) tsc is normally marked unstable very shortly after boot, so only sleepy test can trigger this. I believe it is very bad idea to use tsc, it does not work on 90%+ of machines. Yes, we do detect it is broken during runtime, but that's too late. I believe fix is very simple: Signed-off-by: Pavel Machek Pavel diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index 43517e3..fafd9dc 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -298,7 +298,7 @@ static cycle_t read_tsc(void) static struct clocksource clocksource_tsc = { .name = "tsc", - .rating = 300, + .rating = 0, .read = read_tsc, .mask = CLOCKSOURCE_MASK(64), .mult = 0, /* to be set */ diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c index 947554d..b0148d3 100644 --- a/arch/x86/kernel/tsc_64.c +++ b/arch/x86/kernel/tsc_64.c @@ -306,7 +306,7 @@ static cycle_t __vsyscall_fn vread_tsc(v static struct clocksource clocksource_tsc = { .name = "tsc", - .rating = 300, + .rating = 0, .read = read_tsc, .mask = CLOCKSOURCE_MASK(64), .shift = 22, -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html