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Commit 38e760a1 authored by Joe Korty's avatar Joe Korty Committed by Thomas Gleixner
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x86: expand /proc/interrupts to include missing vectors, v2 



Add missing IRQs and IRQ descriptions to /proc/interrupts.

/proc/interrupts is most useful when it displays every IRQ vector in use by
the system, not just those somebody thought would be interesting.

This patch inserts the following vector displays to the i386 and x86_64
platforms, as appropriate:

	rescheduling interrupts
	TLB flush interrupts
	function call interrupts
	thermal event interrupts
	threshold interrupts
	spurious interrupts

A threshold interrupt occurs when ECC memory correction is occuring at too
high a frequency.  Thresholds are used by the ECC hardware as occasional
ECC failures are part of normal operation, but long sequences of ECC
failures usually indicate a memory chip that is about to fail.

Thermal event interrupts occur when a temperature threshold has been
exceeded for some CPU chip.  IIRC, a thermal interrupt is also generated
when the temperature drops back to a normal level.

A spurious interrupt is an interrupt that was raised then lowered by the
device before it could be fully processed by the APIC.  Hence the apic sees
the interrupt but does not know what device it came from.  For this case
the APIC hardware will assume a vector of 0xff.

Rescheduling, call, and TLB flush interrupts are sent from one CPU to
another per the needs of the OS.  Typically, their statistics would be used
to discover if an interrupt flood of the given type has been occuring.

AK: merged v2 and v4 which had some more tweaks
AK: replace Local interrupts with Local timer interrupts
AK: Fixed description of interrupt types.

[ tglx: arch/x86 adaptation ]
[ mingo: small cleanup ]

Signed-off-by: default avatarJoe Korty <joe.korty@ccur.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Cc: Tim Hockin <thockin@hockin.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 9aa8d719

Documentation/filesystems/proc.txt

+29 −1
Original line number Diff line number Diff line
@@ -347,7 +347,35 @@ connects the CPUs in a SMP system. This means that an error has been detected, 
the IO-APIC automatically retry the transmission, so it should not be a big

problem, but you should read the SMP-FAQ.



In this context it could be interesting to note the new irq directory in 2.4.

In 2.6.2* /proc/interrupts was expanded again.  This time the goal was for

/proc/interrupts to display every IRQ vector in use by the system, not

just those considered 'most important'.  The new vectors are:



  THR -- interrupt raised when a machine check threshold counter

  (typically counting ECC corrected errors of memory or cache) exceeds

  a configurable threshold.  Only available on some systems.



  TRM -- a thermal event interrupt occurs when a temperature threshold

  has been exceeded for the CPU.  This interrupt may also be generated

  when the temperature drops back to normal.



  SPU -- a spurious interrupt is some interrupt that was raised then lowered

  by some IO device before it could be fully processed by the APIC.  Hence

  the APIC sees the interrupt but does not know what device it came from.

  For this case the APIC will generate the interrupt with a IRQ vector

  of 0xff. This might also be generated by chipset bugs.



  RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are

  sent from one CPU to another per the needs of the OS.  Typically,

  their statistics are used by kernel developers and interested users to

  determine the occurance of interrupt of the given type.



The above IRQ vectors are displayed only when relevent.  For example,

the threshold vector does not exist on x86_64 platforms.  Others are

suppressed when the system is a uniprocessor.  As of this writing, only

i386 and x86_64 platforms support the new IRQ vector displays.



Of some interest is the introduction of the /proc/irq directory to 2.4.

It could be used to set IRQ to CPU affinity, this means that you can "hook" an

IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the

irq subdir is one subdir for each IRQ, and one file; prof_cpu_mask

arch/x86/kernel/apic_32.c

+1 −0
Original line number Diff line number Diff line
@@ -1277,6 +1277,7 @@ void smp_spurious_interrupt(struct pt_regs *regs) 
	/* see sw-dev-man vol 3, chapter 7.4.13.5 */

	printk(KERN_INFO "spurious APIC interrupt on CPU#%d, "

	       "should never happen.\n", smp_processor_id());

	__get_cpu_var(irq_stat).irq_spurious_count++;

	irq_exit();

}

arch/x86/kernel/apic_64.c

+1 −0
Original line number Diff line number Diff line
@@ -1140,6 +1140,7 @@ asmlinkage void smp_spurious_interrupt(void) 
	if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))

		ack_APIC_irq();



	add_pda(irq_spurious_count, 1);

	irq_exit();

}

arch/x86/kernel/cpu/mcheck/p4.c

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ fastcall void smp_thermal_interrupt(struct pt_regs *regs) 
{

	irq_enter();

	vendor_thermal_interrupt(regs);

	__get_cpu_var(irq_stat).irq_thermal_count++;

	irq_exit();

}

arch/x86/kernel/irq_32.c

+29 −2
Original line number Diff line number Diff line
@@ -280,14 +280,41 @@ int show_interrupts(struct seq_file *p, void *v) 
		seq_printf(p, "NMI: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ", nmi_count(j));

		seq_putc(p, '\n');

		seq_printf(p, "  Non-maskable interrupts\n");

#ifdef CONFIG_X86_LOCAL_APIC

		seq_printf(p, "LOC: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

				per_cpu(irq_stat,j).apic_timer_irqs);

		seq_putc(p, '\n');

		seq_printf(p, "  Local timer interrupts\n");

#endif

#ifdef CONFIG_SMP

		seq_printf(p, "RES: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

				per_cpu(irq_stat,j).irq_resched_count);

		seq_printf(p, "  Rescheduling interrupts\n");

		seq_printf(p, "CAL: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

				per_cpu(irq_stat,j).irq_call_count);

		seq_printf(p, "  function call interrupts\n");

		seq_printf(p, "TLB: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

				per_cpu(irq_stat,j).irq_tlb_count);

		seq_printf(p, "  TLB shootdowns\n");

#endif

		seq_printf(p, "TRM: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

				per_cpu(irq_stat,j).irq_thermal_count);

		seq_printf(p, "  Thermal event interrupts\n");

		seq_printf(p, "SPU: ");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

				per_cpu(irq_stat,j).irq_spurious_count);

		seq_printf(p, "  Spurious interrupts\n");

		seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));

#if defined(CONFIG_X86_IO_APIC)

		seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));