From owner-freebsd-performance@FreeBSD.ORG Wed Mar 22 18:21:59 2006 Return-Path: X-Original-To: freebsd-performance@freebsd.org Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 77B2216A426 for ; Wed, 22 Mar 2006 18:21:59 +0000 (UTC) (envelope-from g_jin@lbl.gov) Received: from smtp101.sbc.mail.mud.yahoo.com (smtp101.sbc.mail.mud.yahoo.com [68.142.198.200]) by mx1.FreeBSD.org (Postfix) with SMTP id 5CE0143D62 for ; Wed, 22 Mar 2006 18:21:56 +0000 (GMT) (envelope-from g_jin@lbl.gov) Received: (qmail 62627 invoked from network); 22 Mar 2006 18:21:55 -0000 Received: from unknown (HELO ?192.168.2.10?) (jinmtb@sbcglobal.net@68.127.178.44 with plain) by smtp101.sbc.mail.mud.yahoo.com with SMTP; 22 Mar 2006 18:21:55 -0000 Message-ID: <44219619.7020900@lbl.gov> Date: Wed, 22 Mar 2006 10:23:21 -0800 From: "Jin Guojun [VFFS]" User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.5) Gecko/20050108 X-Accept-Language: zh, zh-CN, en To: Arne Woerner References: <20060322175336.59008.qmail@web30309.mail.mud.yahoo.com> In-Reply-To: <20060322175336.59008.qmail@web30309.mail.mud.yahoo.com> Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Wed, 22 Mar 2006 21:22:24 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-performance@freebsd.org, Gary Thorpe , oxy@field.hu Subject: Re: packet drop with intel gigabit / marwell gigabit X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Mar 2006 18:21:59 -0000 Arne Woerner wrote: It depends on how you use /dev/zero. dd of=/dev/null if=/dev/zero bs=4k count=100k tests cache speed % dd of=/dev/null if=/dev/zero bs=4k count=100k 102400+0 records in 102400+0 records out 419430400 bytes transferred in 0.204511 secs (2050894814 bytes/sec) about 32Gbit/sec? If you have 1.8-19.GHz 32-bit CPU with 2 level caches, 16 Gb/s cache speed is about right, not 32 (2x8=16). dd of=/dev/null if=/dev/zero bs=4m count=100 tests memory bandwidth if your cache is less than 2 MB % dd of=/dev/null if=/dev/zero bs=4m count=100 100+0 records in 100+0 records out 419430400 bytes transferred in 2.587341 secs (162108677 bytes/sec) about 2.4Gbit/sec? I had an mpeg encoder in the background, when i did those benchmarks... :-) Now you may give me the real memory bandwidth on your system :-) I would expect something around 500. Hmm... 500Mbit/sec? even if i divide 2.4Gbit by 4, i still get 600Mbit/sec on a quite busy (50%) system... All previous notations are MB, not Mb. Also, 1 Byte is 8 bits not 4 bits. :-) Even after your program finished, you had only 277 MB/s (DDR memory?), which is far below a good motherboard. Good motherboards should have 500 - 900 MB/s memory bandwidth, while expensive motherboards can have 1-3 GB/s memory bandwidth, which are suitable for 10 Gb/s NIC. It sounds like you have a A7V8X or similar motherboard, Do you? -Jin