linux-kernel - [patch 0/2] genirq, proc: Speedup /proc/stat interrupt statistics

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Message-Id: <20190130123130.785636313@linutronix.de>
Date:   Wed, 30 Jan 2019 13:31:30 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Waiman Long <longman@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Kees Cook <keescook@...omium.org>,
        linux-fsdevel@...r.kernel.org, Davidlohr Bueso <dave@...olabs.net>,
        Miklos Szeredi <miklos@...redi.hu>,
        Daniel Colascione <dancol@...gle.com>,
        Dave Chinner <david@...morbit.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Marc Zyngier <marc.zyngier@....com>
Subject: [patch 0/2] genirq, proc: Speedup /proc/stat interrupt statistics

Waiman reported that on large systems with a large amount of interrupts the
readout of /proc/stat takes a long time to sum up the interrupt
statistics. In principle this is not a problem. but for unknown reasons
some enterprise quality software reads /proc/stat with a high frequency.

The reason for this is that interrupt statistics are accounted per cpu. So
the /proc/stat logic has to sum up the interrupt stats for each interrupt.

The following series addresses this by making the interrupt statitics code
in the core generate the sum directly and by making the loop in the
/proc/stat read function smarter.

Thanks,

	tglx

8<----------------
 fs/proc/stat.c          |   28 +++++++++++++++++++++++++---
 include/linux/irqdesc.h |    3 ++-
 kernel/irq/chip.c       |   12 ++++++++++--
 kernel/irq/internals.h  |    8 +++++++-
 kernel/irq/irqdesc.c    |    7 ++++++-
 5 files changed, 50 insertions(+), 8 deletions(-)