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Date: Sat, 9 Sep 2000 00:18:34 -0700
From: Alfred Perlstein <bright@wintelcom.net>
To: Julian Elischer <julian@elischer.org>
Cc: net@freebsd.org
Subject: Re: threading tcp/ip is fun.
Message-ID: <20000909001833.M12231@fw.wintelcom.net>
References: <20000908154320.J12231@fw.wintelcom.net> <39B9CC11.41C67EA6@elischer.org>
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* Julian Elischer <julian@elischer.org> [000908 22:35] wrote:
> Alfred Perlstein wrote:
> > 
> > http://www.wintelcom.net/~bright/thrsock.diff
> > 
> > Should refresh every two minutes as I progress through the tcp/ip
> > code in an attempt to thread it.
> > 
> > If you have suggestions or works in progress please let me know.
> 
> 
> There is a lot of use of "atomic_ad_long()"
> nearly always with an increment of '1'.
> Would there be any advantage of having an
> "atomic_increment_long()"?
>  (a_incl())
> 
> with the introduction of heavier weight operations at low level 
> (e.g."atomic_add_long(a , 1);" vs "a += 1;"
> the optimal way if unrolling loops and threading decision
> trees may change..
> 
> e.g.
> 
> if (XXX)
>    a_incl(a);
> if (YYY)
>    a_incl(b);
> if (ZZZ)
>    a_incl(c);
> 
> might be slower than:
> small_lock()
> if (XXX)a+=1;
> if (YYY)b+=1;
> if (ZZZ)c+=1;
> drop_small_lock();
> 
> (in this case not likely, but it's something to keep in mind I guess.)

Actually it's very good idea, however, right now I'm just trying
to get it SMP safe, at a later date we may want to keep CPU private
counters and in one operation update the tcpstat struct on exit
from the routine.

-Alfred


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