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Date:      Thu, 10 Dec 1998 11:31:55 -0500 (EST)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        freebsd-current@FreeBSD.ORG
Subject:   Re: increased UDP latencies in -current
Message-ID:  <13935.62856.525786.504663@grasshopper.cs.duke.edu>
In-Reply-To: <199812101613.DAA16454@godzilla.zeta.org.au>
References:  <199812101613.DAA16454@godzilla.zeta.org.au>

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Bruce Evans writes:
 > >In the process of doing some Myrinet benchmarks, I noticed that UDP
 > >latencies have increased markedly after upgrading from 2.2.5-stable to
 > >3.0-current.
 > 
 > I see the opposite of this, if anything, for -current vs 2.2.6-2.2.7.

Hmm..  Perhaps my 2.2.5 kernel was built before the change responsible 
for the increased latencies was committed.

< .. >

 > 
 > On a K6/233, VIA2 chipset:
 > 				lmbench-1.x "lat_udp localhost"
 > 				--------
 > 2.2.5-2.2.6			about 85
 > -current			about 80

lmbench 1-x shows similar results to what I saw with hbench:

2.2.5		54
-current	65


 > Other not very careful lmbench-2 tests show a 10% UDP time bloat in my
 > version of -current over the last 18 months:
 > 
 > *Local* Communication latencies in microseconds - smaller is better
 > -------------------------------------------------------------------
 > Host                 OS 2p/0K  Pipe AF     UDP  RPC/   TCP  RPC/ TCP
 >                         ctxsw       UNIX         UDP         TCP conn
 > --------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
 > gamplex.b FreeBSD 2.2.6     9    34   41    85   155    91   199  351
 > gamplex.b FreeBSD 3.0-C    14    30   32    71   161    79   202  575
 > gamplex.b FreeBSD 3.0-C    13    28   31    70          75   190  653
 > gamplex.b FreeBSD 3.0-C     7    26   33    79          91   207     
 > gamplex.b FreeBSD 3.0-C     7    27   34    74          83   209     
 > gamplex.b FreeBSD 3.0-C     7    29   34    78          85   207     
 > gamplex.b FreeBSD 3.0-C     7    26   35    85          80   211     
 > gamplex.b FreeBSD 3.0-C     8    27   35    88          79           
 > gamplex.b FreeBSD 3.0-C     5    25   36    75   161    77   217     
 > gamplex.b FreeBSD 3.0-C     7    27   36    82   176    85   216     
 > gamplex.b FreeBSD 3.0-C     6    27   35    80          82   210     
 > gamplex.b Linux 2.1.128     6    28   52    74   169    92   222     


What are the differences between the many 'FreeBSD 3.0-C' entries?  Is
it is primarily the date their kernel sources were checked out? Do you
have approximate dates?

Thanks,

Drew

------------------------------------------------------------------------------
Andrew Gallatin, Sr Systems Programmer	http://www.cs.duke.edu/~gallatin
Duke University				Email: gallatin@cs.duke.edu
Department of Computer Science		Phone: (919) 660-6590


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