linux-kernel - Re: [PATCH] fs/proc: introduce /proc/stat2 file

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Date:   Wed, 7 Nov 2018 23:24:02 -0800
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Dave Chinner <david@...morbit.com>
Cc:     Miklos Szeredi <miklos@...redi.hu>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Daniel Colascione <dancol@...gle.com>, longman@...hat.com,
        linux-fsdevel@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH] fs/proc: introduce /proc/stat2 file

On Thu, 08 Nov 2018, Dave Chinner wrote:

>If only we had percpu counters that had a fixed, extremely low read
>overhead that doesn't care about the number of CPUs in the
>machine....
>
>Oh, wait, we do: percpu_counters.[ch].
>
>This all seems like a counter implementation deficiency to me, not
>an interface problem...

Yeah fair point, as long as we can sacrifice accuracy by replacing
kernel_stat -- or maybe just replace the hard irq stats, which I
still think only accounts for 1% of all stat users. I have not looked
at how filesystems tune the batch size, but it would certainly be worth
looking into methinks.

Thanks,
Davidlohr