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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Waiman Long <longman@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	linux-fsdevel@vger.kernel.org,
	Davidlohr Bueso <dave@stgolabs.net>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Daniel Colascione <dancol@google.com>,
	Dave Chinner <david@fromorbit.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Marc Zyngier <marc.zyngier@arm.com>
Subject: [patch V2 0/2] genirq, proc: Speedup /proc/stat interrupt statistics
Date: Fri, 08 Feb 2019 14:48:02 +0100
Message-ID: <20190208134802.218483159@linutronix.de> (raw)

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.

V1 -> V2: Address review feedback: undo struct layout changes, make
      	  variables unsigned and add test results to the changelog.

Thanks,

        tglx

8<----------------
 fs/proc/stat.c          |   29 ++++++++++++++++++++++++++---
 include/linux/irqdesc.h |    1 +
 kernel/irq/chip.c       |   12 ++++++++++--
 kernel/irq/internals.h  |    8 +++++++-
 kernel/irq/irqdesc.c    |    7 ++++++-
 5 files changed, 50 insertions(+), 7 deletions(-)


             reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-08 13:48 Thomas Gleixner [this message]
2019-02-08 13:48 ` [patch V2 1/2] genriq: Avoid summation loops for /proc/stat Thomas Gleixner
2019-02-08 22:32   ` Andrew Morton
2019-02-08 22:46     ` Waiman Long
2019-02-08 23:21       ` Andrew Morton
2019-02-09  3:41         ` Matthew Wilcox
2019-02-13 15:55           ` David Laight
2019-02-08 13:48 ` [patch V2 2/2] proc/stat: Make the interrupt statistics more efficient Thomas Gleixner
2019-02-08 17:01   ` Alexey Dobriyan
2019-02-08 15:20 ` [patch V2 0/2] genirq, proc: Speedup /proc/stat interrupt statistics Waiman Long
2019-02-08 17:01 ` Davidlohr Bueso
2019-02-08 17:40 ` Marc Zyngier

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