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Date:      Thu, 25 Apr 2013 11:30:34 -0700
From:      Adrian Chadd <adrian@freebsd.org>
To:        Andre Oppermann <andre@freebsd.org>
Cc:        =?ISO-8859-1?Q?Olivier_Cochard=2DLabb=E9?= <olivier@cochard.me>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, Sami Halabi <sodynet1@gmail.com>
Subject:   Re: forwarding/ipfw/pf evolution (in pps) on -current
Message-ID:  <CAJ-VmomqxeyePZjORw8A5Q8m6PM5hOh2148xX90r9xPj9rhxxA@mail.gmail.com>
In-Reply-To: <5178F72F.90008@freebsd.org>
References:  <CA%2Bq%2BTcpghAtae7%2BuXehxP9%2BtNh1TiTzxOShDNkLt_xSrgoBGdA@mail.gmail.com> <CAEW%2BogY%2BOmtqS7S1OOHXL8LnYSur5nfpJnvi=aM6vjCKH124Hw@mail.gmail.com> <CA%2Bq%2BTcpRZ_Dc=WTE522zWZ54VviaoQPsRT8%2BgWM%2BoRk5nUpOkg@mail.gmail.com> <5178F72F.90008@freebsd.org>

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On 25 April 2013 02:28, Andre Oppermann <andre@freebsd.org> wrote:

> Again one has to be really careful drawing any firm conclusions from this
> as it was measured on a Pentium4 and UP kernel (GENERIC would add WITNESS
> and INVARIANT overhead as well).
>
> The Pentium4 is about the worst micro-architecture when it comes to locks
> and easily regresses.  At the same time modern Intel Core i[3-7] and AMD64
> may actually improve with these changes.  Unless more recent micro-archs
> have been shown to exhibit the same regression we can't claim this change
> was bad (other than for Pentium4).

Sure, but he's done the heavy lifting.

It'll be interesting to compare these results on a variety of
platforms, not just the modern desktop/server style CPUs.

Eg, if someone has the time, spinning this stuff up on the multi-core
MIPS stuff in the netperf cluster (that's supposed to be a network
forwarding engine) would be nice.

And to be honest - having a set of performance checks for the same SVN
revision but different physical machines is a good comparison point.
It may be that we can start classifying different kinds of platform
silliness from this which could lead to some better coding guidelines.


Adrian



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