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Date:      Wed, 13 Sep 2017 15:32:31 -0700
From:      Gleb Smirnoff <glebius@FreeBSD.org>
To:        Mateusz Guzik <mjguzik@gmail.com>
Cc:        Bruce Evans <brde@optusnet.com.au>, Mateusz Guzik <mjg@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>
Subject:   Re: svn commit: r323393 - in head/sys: sys vm
Message-ID:  <20170913223231.GN1055@FreeBSD.org>
In-Reply-To: <CAGudoHG8yVw46cwmpswnozMf-pSjHtBXHDk8DmJ6v=CwOCvWLg@mail.gmail.com>
References:  <201709101900.v8AJ0c2N059845@repo.freebsd.org> <20170911111127.B870@besplex.bde.org> <CAGudoHG8yVw46cwmpswnozMf-pSjHtBXHDk8DmJ6v=CwOCvWLg@mail.gmail.com>

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On Mon, Sep 11, 2017 at 09:30:10AM +0200, Mateusz Guzik wrote:
M> First, there is a bunch of counter(9) fields. I don't know the original
M> reasoning. I would expect these counters to be statically defined in a
M> per-cpu struct.

The reasoning was to remove 'struct vmmeter' from the 'struct pcpu', which
sounds inline with your desire to remote struct vmmeter from the kernel
at all.

Maintainance wise, it is much easier not to bloat 'struct pcpu' with
various global statistics, but keep them as counter(9)s instead. Indeed,
what's the big difference between TCP statistics and VM statistics, why
treat them differently?

Performance wise, I haven't seen any regressions when collapsed
multiple entities of struct vmmeter sitting in struct pcpu, into
single one with counter(9)s.

-- 
Gleb Smirnoff



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