linux-kernel - Re: [PATCH] x86: add show

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Message-ID: <86802c440909281046o5fa0032do3497087d173cbf82@mail.gmail.com>
Date:	Mon, 28 Sep 2009 10:46:54 -0700
From:	Yinghai Lu <yhlu.kernel@...il.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: add show_lapic=

On Mon, Sep 28, 2009 at 9:07 AM, Cyrill Gorcunov <gorcunov@...il.com> wrote:
> Yinghai, if you still need show_lapic=1 by default the
> acceptable solution (I guess) could be that we accept
> show_lapic=all as well. So a user may safely put it without
> knowing how many apics he has.
>
> Does it look acceptable for you? Something like (tested) below.
> Also I think maybe we should better extend apic= option itself instead
> of intruducing new one?
>
> Anyway, what you think? (again, if you like this patch -- SOB it, Ack it,
> or whatever you want).
> ---
> [PATCH -tip] x86,apic: limit apic dumping, introduce show_lapic setup option
>
> In case if a system has a large number of cpus printing apics
> contents may consume a long time period.
>
> We limit such an output by 1 apic by default. But to have an
> ability to see all apics or some part of them we introduce
> "show_lapic" setup option which allow us to limit/unlimit
> the number of APICs being dumped.
>
> Example: apic=debug show_lapic=5, or apic=debug show_lapic=all
>
> Also move apic_verbosity checking upper that way so helper routines
> do not need to inspect it at all.
>
> Suggested-by: Yinghai Lu <yinghai@...nel.org>
> Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
> ---
>  arch/x86/kernel/apic/io_apic.c |   47 +++++++++++++++++++++++++++--------------
>  1 file changed, 32 insertions(+), 15 deletions(-)
>
> Index: linux-2.6.git/arch/x86/kernel/apic/io_apic.c
> =====================================================================
> --- linux-2.6.git.orig/arch/x86/kernel/apic/io_apic.c
> +++ linux-2.6.git/arch/x86/kernel/apic/io_apic.c
> @@ -1599,9 +1599,6 @@ __apicdebuginit(void) print_IO_APIC(void
>        struct irq_desc *desc;
>        unsigned int irq;
>
> -       if (apic_verbosity == APIC_QUIET)
> -               return;
> -
>        printk(KERN_DEBUG "number of MP IRQ sources: %d.\n", mp_irq_entries);
>        for (i = 0; i < nr_ioapics; i++)
>                printk(KERN_DEBUG "number of IO-APIC #%d registers: %d.\n",
> @@ -1708,9 +1705,6 @@ __apicdebuginit(void) print_APIC_field(i
>  {
>        int i;
>
> -       if (apic_verbosity == APIC_QUIET)
> -               return;
> -
>        printk(KERN_DEBUG);
>
>        for (i = 0; i < 8; i++)
> @@ -1724,9 +1718,6 @@ __apicdebuginit(void) print_local_APIC(v
>        unsigned int i, v, ver, maxlvt;
>        u64 icr;
>
> -       if (apic_verbosity == APIC_QUIET)
> -               return;
> -
>        printk(KERN_DEBUG "printing local APIC contents on CPU#%d/%d:\n",
>                smp_processor_id(), hard_smp_processor_id());
>        v = apic_read(APIC_ID);
> @@ -1824,13 +1815,19 @@ __apicdebuginit(void) print_local_APIC(v
>        printk("\n");
>  }
>
> -__apicdebuginit(void) print_all_local_APICs(void)
> +__apicdebuginit(void) print_local_APICs(int maxcpu)
>  {
>        int cpu;
>
> +       if (!maxcpu)
> +               return;
> +
>        preempt_disable();
> -       for_each_online_cpu(cpu)
> +       for_each_online_cpu(cpu) {
> +               if (cpu >= maxcpu)
> +                       break;
>                smp_call_function_single(cpu, print_local_APIC, NULL, 1);
> +       }
>        preempt_enable();
>  }
>
> @@ -1839,7 +1836,7 @@ __apicdebuginit(void) print_PIC(void)
>        unsigned int v;
>        unsigned long flags;
>
> -       if (apic_verbosity == APIC_QUIET || !nr_legacy_irqs)
> +       if (!nr_legacy_irqs)
>                return;
>
>        printk(KERN_DEBUG "\nprinting PIC contents\n");
> @@ -1866,21 +1863,41 @@ __apicdebuginit(void) print_PIC(void)
>        printk(KERN_DEBUG "... PIC ELCR: %04x\n", v);
>  }
>
> -__apicdebuginit(int) print_all_ICs(void)
> +static int __initdata show_lapic = 1;
> +static __init int setup_show_lapic(char *arg)
> +{
> +       int num = -1;
> +
> +       if (strcmp(arg, "all") == 0) {
> +               show_lapic = CONFIG_NR_CPUS;

NR_CPUS or nr_cpu_ids?

YH
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