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 <[EMAIL PROTECTED]> wrote: > > > On Tue, Feb 26, 2008 at 1:22 PM, Randy Dunlap <[EMAIL PROTECTED]> wrote: > > > > On Mon, 25 Feb 2008 10:14:36 +0800 Dave Young wrote: > > > > > > > > > On Sun, Feb 24, 2008 at 8:46 AM, Dave Jones <[EMAIL PROTECTED]> > > > 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). 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... 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? 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 [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
