Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764784AbYB0CB5 (ORCPT ); Tue, 26 Feb 2008 21:01:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752464AbYB0CBt (ORCPT ); Tue, 26 Feb 2008 21:01:49 -0500 Received: from ti-out-0910.google.com ([209.85.142.190]:18509 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751971AbYB0CBs (ORCPT ); Tue, 26 Feb 2008 21:01:48 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=gnymTuNDX11XeOfXbzjZuF51IOl9FUhpHLS2uRUvyTuNzIq/kwHXD1mpzoHvDJjLmpuaKVpgz/5bKSHQGNHSvtW2vf+NrQ7PqSV2bPC5z6BQ01w0MvQG6cMJYbe+A6c2kbzZnMAsiZA2dis7UBe6hfaJEwWvk/Tw/COuApYGYVk= Message-ID: Date: Wed, 27 Feb 2008 10:01:43 +0800 From: "Dave Young" To: "Randy Dunlap" Subject: Re: boot_delay broken ? Cc: akpm , "Dave Jones" , "Linux Kernel" , "Thomas Gleixner" In-Reply-To: <20080226093323.71ae516b.randy.dunlap@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080224004615.GA31012@codemonkey.org.uk> <20080225212251.18c4659e.randy.dunlap@oracle.com> <20080226090948.GA2794@darkstar.te-china.tietoenator.com> <20080226093323.71ae516b.randy.dunlap@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5639 Lines: 150 On Wed, Feb 27, 2008 at 1:33 AM, Randy Dunlap wrote: > > On Tue, 26 Feb 2008 17:09:48 +0800 Dave Young wrote: > > > On Tue, Feb 26, 2008 at 01:59:31PM +0800, Dave Young wrote: > > > On Tue, Feb 26, 2008 at 1:48 PM, Dave Young wrote: > > > > On Tue, Feb 26, 2008 at 1:22 PM, Randy Dunlap wrote: > > > > > On Mon, 25 Feb 2008 10:14:36 +0800 Dave Young wrote: > > > > > > > > > > > On Sun, Feb 24, 2008 at 8:46 AM, Dave Jones wrote: > > > > > > > The boot_delay switch seems to be behaving strangely in the > > > > > > > current -git. Setting it to =10 makes the output 'bursty' > > > > > > > it becomes slow for some printk's whilst others scroll by > > > > > > > at regular speed. > > > > > > > Setting it any higher than that seems to make it pause for > > > > > > > a really long time before it outputs any text at all. > > > > > > > > > > > > On my side there's this issue for a long time > > > > > > http://lkml.org/lkml/2007/8/8/79 > > > > > > > > > > [http://marc.info/?l=linux-kernel&m=118655896515049&w=2] > > > > > > > > > > You asked questions and they were answered. Perhaps you didn't like > > > > > the answers. > > > > > > > > No, I like it. Thanks. > > > > > > > > But I still want to know why mdelay can not be used. > > > > is it not available for all archs or something else? > > > > > > > > > > > > > > > > > > Here's a question for you. What kernel boot options did you use? > > > > > Specifically, for lpj= and boot_delay= ? > > > > > > > > I tried boot_delay=100 and boot_delay=200 without lpj set, The result > > > > was really slow. It was better with lpj copied from dmesg, but was > > > > still slower then mdelay. > > > > > > Especially at the very beginning after the message "Booting the kernel", > > > I need to wait several minutes to see the afterwards messages > > > > > > > > > > > I think we can firstly use preset lpj, after delay calibrating just > > > > use the system lpj > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > x86 timer changes perhaps ? > > > > > > > > > > > > > > > --- > > > > > ~Randy > > > > > > > > > > > > > How about use loops_per_jiffy as following? With this patch at least > > for me the very long delay at the very begining does not occur. > > > > kernel/printk.c | 15 ++++----------- > > 1 file changed, 4 insertions(+), 11 deletions(-) > > > > diff -upr linux/kernel/printk.c linux.new/kernel/printk.c > > --- linux/kernel/printk.c 2008-02-26 16:54:23.000000000 +0800 > > +++ linux.new/kernel/printk.c 2008-02-26 16:59:02.000000000 +0800 > > @@ -173,24 +173,14 @@ __setup("log_buf_len=", log_buf_len_setu > > #ifdef CONFIG_BOOT_PRINTK_DELAY > > > > static unsigned int boot_delay; /* msecs delay after each printk during bootup */ > > -static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ > > > > static int __init boot_delay_setup(char *str) > > { > > - unsigned long lpj; > > - unsigned long long loops_per_msec; > > - > > - lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ > > - loops_per_msec = (unsigned long long)lpj / 1000 * HZ; > > - > > get_option(&str, &boot_delay); > > if (boot_delay > 10 * 1000) > > boot_delay = 0; > > > > - printk_delay_msec = loops_per_msec; > > - printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " > > - "HZ: %d, printk_delay_msec: %llu\n", > > - boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); > > + printk(KERN_DEBUG "boot_delay: %u\n", boot_delay); > > return 1; > > } > > __setup("boot_delay=", boot_delay_setup); > > @@ -199,6 +189,9 @@ static void boot_delay_msec(void) > > { > > unsigned long long k; > > unsigned long timeout; > > + unsigned long long printk_delay_msec; > > + > > + printk_delay_msec = (unsigned long long)loops_per_jiffy / 1000 * HZ; > > > > if (boot_delay == 0 || system_state != SYSTEM_BOOTING) > > return; > > -- > > Hi Dave, > > That might work, but IMO it requires someone to audit all > architectures to make sure that loops_per_jiffy has been calibrated > at that point in time >(as I mentioned in http://lkml.org/lkml/2007/8/11/153). Sorry for missing your words about this. > > I didn't do that and you said that you tested i386 only. > > Maybe you can get Andrew to merge it into -mm for testing... Andrew, what's your opinon? > > However, setting boot_delay=N without setting lpj=M is just not > advisable. The Kconfig help text for BOOT_PRINTK_DELAY tries to > say that. Maybe it needs to be stronger? I think it's enough now. I tested boot_delay yestoday, and found the result is different with before version. Even with lpj preset the delay is very slow, 5-10 seconds for every printk. Maybe this is what davej said. I will do some more test and hack about this today. > > It is likely that you would also need to use "lpj=M" to preset > the "loops per jiffie" value. > See a previous boot log for the "lpj" value to use for your > system, and then set "lpj=M" before setting "boot_delay=N". > > > --- > ~Randy > -- 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/