Date: Sat, 16 Jun 2001 14:14:14 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Rik van Riel <riel@conectiva.com.br> Cc: Matthew Hagerty <mhagerty@voyager.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: Article: Network performance by OS Message-ID: <200106162114.f5GLEEg02073@earth.backplane.com> References: <Pine.LNX.4.21.0106161712060.2056-100000@imladris.rielhome.conectiva>
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:The only thing that worries me a bit is that both FreeBSD
:and Linux needed to be tuned at all to run these things,
:even if it was just the maximum file descriptor setting.
:
:A lot of this tuning could easily be done dynamically
:(and is done dynamically on linux 2.4), but lots of it
:still has static maximums which have to be tuned by hand.
:Compile-time tuning for stuff which can be dynamically
:allocated (and freed) is IMHO a big sillyness in the OS.
:
:
:Yes, this report was completely useless as a benchmark,
:but it DID highlight a point where Linux and BSD can be
:improved: dynamic allocation (and freeing) of things
:like file descriptors and socket structures.
:
:regards,
:
:Rik
It's certainly true that a greater degree of dynamic tuning could be
done, but all this benchmark proves (in regards to the TCP results)
is that FreeBSD puts its foot down earlier then other OS's in regards
to how much it is willing to dedicate to the network. In a real life
situation where you may be running a multi-user load or a large database,
the very last thing you want to do is shift every last bit of your
resources away from the users or the database and to the network when
an 'unexpected load' comes in (unexpected meaning something that is a
factor of 100 or 1000x what the machine normally handles). The
truth of the matter is that no amount of dynamic tuning can handle
every situation... at some point you have to manually tune the box.
FreeBSD does exactly the right thing on an untuned box by capping the
network resources. If the authors want to run the machine into the
ground with a benchmark, they have to tune the machine properly to handle
the load because FreeBSD anyway is more interested in keeping the
integrity of the machine as a whole together then it is tuning itself
to match some idiot who thinks he is gods own gift to humanity running
a benchmark.
-Matt
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