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From: Alexei Lozovsky <me@ilammy.net>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	Christoph Lameter <cl@linux.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH 0/7] proc/stat: Maintain monotonicity of "intr" and "softirq"
Date: Sat, 11 Sep 2021 12:48:01 +0900	[thread overview]
Message-ID: <20210911034808.24252-1-me@ilammy.net> (raw)
In-Reply-To: <06F4B1B0-E4DE-4380-A8E1-A5ACAD285163@ilammy.net>

Here's a patch set that makes /proc/stat report total interrupt counts
as monotonically increasing values, just like individual counters for
interrupt types and CPUs are.

This is as if the sum was a shared counter that all CPUs increment
atomically together with their individual counters, with the sum
correctly and expectedly wrapping around to zero once it reaches
UINT_MAX.

I've also added some documentation bits to codify this behavior and make
it explicit that wrap-arounds must be expected and handled if userspace
wants to maintain accurate total interrupt count for whatever reasons.

Alexei Lozovsky (7):
  genirq: Use unsigned int for irqs_sum
  powerpc/irq: arch_irq_stat_cpu() returns unsigned int
  x86/irq: arch_irq_stat_cpu() returns unsigned int
  x86/irq: arch_irq_stat() returns unsigned int
  proc/stat: Use unsigned int for "intr" sum
  proc/stat: Use unsigned int for "softirq" sum
  docs: proc.rst: stat: Note the interrupt counter wrap-around

 Documentation/filesystems/proc.rst | 7 +++++++
 arch/powerpc/include/asm/hardirq.h | 2 +-
 arch/powerpc/kernel/irq.c          | 4 ++--
 arch/x86/include/asm/hardirq.h     | 4 ++--
 arch/x86/kernel/irq.c              | 8 ++++----
 fs/proc/stat.c                     | 8 ++++----
 include/linux/kernel_stat.h        | 2 +-
 7 files changed, 21 insertions(+), 14 deletions(-)

-- 
2.25.1


  reply	other threads:[~2021-09-11  3:48 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-10  8:53 /proc/stat interrupt counter wrap-around Alexei Lozovsky
2021-09-11  3:48 ` Alexei Lozovsky [this message]
2021-09-11  3:48   ` [PATCH 1/7] genirq: Use unsigned int for irqs_sum Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 2/7] powerpc/irq: arch_irq_stat_cpu() returns unsigned int Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 3/7] x86/irq: " Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 4/7] x86/irq: arch_irq_stat() " Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 5/7] proc/stat: Use unsigned int for "intr" sum Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 6/7] proc/stat: Use unsigned int for "softirq" sum Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 7/7] docs: proc.rst: stat: Note the interrupt counter wrap-around Alexei Lozovsky
2021-09-11  3:59     ` Randy Dunlap
2021-09-12  9:30   ` [PATCH 0/7] proc/stat: Maintain monotonicity of "intr" and "softirq" Alexey Dobriyan
2021-09-12 12:37     ` Alexei Lozovsky
2021-09-14 14:11       ` Thomas Gleixner
2021-09-15  4:24         ` Alexei Lozovsky
2021-09-15 17:58   ` [PATCH v2 00/12] " Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 01/12] genirq: Use READ_ONCE for IRQ counter reads Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 02/12] genirq: Use unsigned long for IRQ counters Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 03/12] powerpc/irq: Use READ_ONCE for IRQ counter reads Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 04/12] powerpc/irq: Use unsigned long for IRQ counters Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 05/12] powerpc/irq: Use unsigned long for IRQ counter sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 06/12] x86/irq: Use READ_ONCE for IRQ counter reads Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 07/12] x86/irq: Use unsigned long for IRQ counters Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 08/12] x86/irq: Use unsigned long for IRQ counters more Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 09/12] x86/irq: Use unsigned long for IRQ counter sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 10/12] proc/stat: Use unsigned long for "intr" sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 11/12] proc/stat: Use unsigned long for "softirq" sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 12/12] docs: proc.rst: stat: Note the interrupt counter wrap-around Alexei Lozovsky

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