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Subject: Re: [patch V2 0/2] genirq, proc: Speedup /proc/stat interrupt
 statistics
To:     Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     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>
References: <20190208134802.218483159@linutronix.de>
From:   Waiman Long <longman@redhat.com>
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Organization: Red Hat
Message-ID: <43213c22-98fd-c9d4-53a5-21f8ab4fe187@redhat.com>
Date:   Fri, 8 Feb 2019 10:20:03 -0500
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On 02/08/2019 08:48 AM, Thomas Gleixner wrote:
> 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(-)
>
Thanks for the patch.

Reviewed-by: Waiman Long <longman@redhat.com>

-Longman