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    Subject[patch 3/3] 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@kernel.org>
    Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.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;
    + } else {
    + get_option(&arg, &num);
    + if (num >= 0)
    + show_lapic = num;
    + }
    +
    + return 1;
    +}
    +__setup("show_lapic=", setup_show_lapic);
    +
    +__apicdebuginit(int) print_ICs(void)
    {
    + if (apic_verbosity == APIC_QUIET)
    + return 0;
    +
    print_PIC();

    /* don't print out if apic is not there */
    if (!cpu_has_apic && !apic_from_smp_config())
    return 0;

    - print_all_local_APICs();
    + print_local_APICs(show_lapic);
    print_IO_APIC();

    return 0;
    }

    -fs_initcall(print_all_ICs);
    +fs_initcall(print_ICs);


    /* Where if anywhere is the i8259 connect in external int mode */


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