From owner-freebsd-hardware@FreeBSD.ORG Mon Oct 16 17:14:09 2006 Return-Path: X-Original-To: freebsd-hardware@freebsd.org Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id AAED616A403 for ; Mon, 16 Oct 2006 17:14:09 +0000 (UTC) (envelope-from dking@ketralnis.com) Received: from ketralnis.com (melchoir.ketralnis.com [68.183.67.83]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5F12A43D45 for ; Mon, 16 Oct 2006 17:14:09 +0000 (GMT) (envelope-from dking@ketralnis.com) Received: from [192.168.1.87] (pix.xythos.com [64.154.218.194]) (authenticated bits=0) by ketralnis.com (8.13.6/8.13.6) with ESMTP id k9GHE8ns018044 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO) for ; Mon, 16 Oct 2006 10:14:08 -0700 (PDT) (envelope-from dking@ketralnis.com) Mime-Version: 1.0 (Apple Message framework v752.3) In-Reply-To: <200610140346.22554.soralx@cydem.org> References: <78ED28FACE63744386D68D8A9D1CF5D4209C94@MAIL.corp.lumeta.com> <200610140346.22554.soralx@cydem.org> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <301DDDB6-A47E-448F-A145-7B2087599598@ketralnis.com> Content-Transfer-Encoding: 7bit From: David King Date: Mon, 16 Oct 2006 10:14:02 -0700 To: freebsd-hardware@freebsd.org X-Mailer: Apple Mail (2.752.3) Subject: Re: Quiet computer X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Oct 2006 17:14:09 -0000 > BTW, David, test (if you have enough time for curiosity) /dev/ > urandom (or > wherever the generator is) with different values of 'bs', from very > small to large (1 byte, 512, 4k, 16k, 64k) to see how much it depends > on block size. > >> bash-2.05b$ time dd if=/dev/urandom bs=1024 count=10240 of=/dev/null >> 10240+0 records in >> 10240+0 records out >> 10485760 bytes transferred in 0.154649 secs (67803598 bytes/sec) ~% cat test_rand_block.sh #!/usr/local/bin/bash for BS in 1 512 $(expr 1024 \* 4) $(expr 1024 \* 16) $(expr 1024 \* 64); do COUNT=$(expr $(expr 1024 \* 64) / $BS) BYTES=$(expr $COUNT \* $BS) echo bs=$BS count=$COUNT bytes=$BYTES dd if=/dev/random of=/dev/null bs=$BS count=$COUNT echo ------; done ~% sh test_rand_block.sh bs=1 count=65536 bytes=65536 65536+0 records in 65536+0 records out 65536 bytes transferred in 25.599306 secs (2560 bytes/sec) ------ bs=512 count=128 bytes=65536 128+0 records in 128+0 records out 65536 bytes transferred in 0.099902 secs (656003 bytes/sec) ------ bs=4096 count=16 bytes=65536 16+0 records in 16+0 records out 65536 bytes transferred in 0.100660 secs (651062 bytes/sec) ------ bs=16384 count=4 bytes=65536 4+0 records in 4+0 records out 65536 bytes transferred in 0.099324 secs (659820 bytes/sec) ------ bs=65536 count=1 bytes=65536 1+0 records in 1+0 records out 65536 bytes transferred in 0.099681 secs (657458 bytes/sec) ------