Date: Fri, 24 Mar 2006 14:12:01 +0100 From: "OxY" <oxy@field.hu> To: "Jin Guojun [VFFS]" <g_jin@lbl.gov>, "Arne Woerner" <arne_woerner@yahoo.com> Cc: freebsd-performance@freebsd.org, Gary Thorpe <gthorpe@myrealbox.com> Subject: Re: packet drop with intel gigabit / marwell gigabit Message-ID: <003301c64f44$89fdcd40$0201a8c0@oxy> References: <20060322071023.70808.qmail@web30305.mail.mud.yahoo.com> <442187FE.3060300@lbl.gov>
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hi guys!
well, i changed my motherboard and CPU from the
asus a7v8x+amd 2000+ xp to=20
the abit be7 + p4 2.4 (533fsb) and the packet loss fell down from 8% to =
2%, but
still have loss...
loss coming when i have load.. i guess it decreased because of the =
bigger resources.
still waiting for tipps, hints, everything :)
----- Original Message -----=20
From: Jin Guojun [VFFS]=20
To: Arne Woerner=20
Cc: Gary Thorpe ; freebsd-performance@freebsd.org ; oxy@field.hu=20
Sent: Wednesday, March 22, 2006 6:23 PM
Subject: Re: packet drop with intel gigabit / marwell gigabit
Arne Woerner wrote:=20
--- "Jin Guojun [VFFS]" <g_jin@lbl.gov> wrote:
In you example:
Now your 1.6 GB/s reduced to 16MB/s or even worse just based
on this factor.
What did we show by this <<dd if=3D/dev/zero ...>> test? I thought
that would prove the memory bandwidth is about 8Gbit/sec
(1GByte/sec; 2 * <dd's bytes/sec number>/2^30).
It depends on how you use /dev/zero.=20
dd of=3D/dev/null if=3D/dev/zero bs=3D4k count=3D100k
tests cache speed
dd of=3D/dev/null if=3D/dev/zero bs=3D4m count=3D100
tests memory bandwidth if your cache is less than 2 MB
Now you may give me the real memory bandwidth on your system :-)
I would expect something around 500.
Notice that your memory copy speed will be one half of it.=20
/dev/null device really does nothing beside throwing away data.
That is, it can be counted as a cost for system call.
-Jin
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