From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from Ishtar.sc.tlinx.org (ishtar.tlinx.org [173.164.175.65]) by sourceware.org (Postfix) with ESMTPS id 24BF239BE829 for ; Thu, 10 Jun 2021 01:20:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 24BF239BE829 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=tlinx.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tlinx.org Received: from [192.168.3.12] (Athenae [192.168.3.12]) by Ishtar.sc.tlinx.org (8.14.7/8.14.4/SuSE Linux 0.8) with ESMTP id 15A1KBPC056559 for ; Wed, 9 Jun 2021 18:20:17 -0700 Message-ID: <60C168AF.4070400@tlinx.org> Date: Wed, 09 Jun 2021 18:19:43 -0700 From: L A Walsh User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: "cygwin@cygwin.com" Subject: odd prob for cygwin 'dd' from a character device on network disk Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Jun 2021 01:20:42 -0000 I've been using a character device on linux in my home directory named 'zero' that is a copy of the 'zero' device in /dev: crwxrwxrw- 1 1, 5 Jun 15 2015 zero to do read benchmarks using 'dd' (and write benchmarks using a file named 'null' thats a copy of /dev/null). I run it "occasionally", but not on a regular basis, since it stays a bit boring. Nevertheless, ballpark numbers consistent with historical norms verify correct network function (separate from read/write files). Read/write speeds at last check a few weeks ago were typical with reads at 700MB/s and writes at about 300MB/s. A few hours ago I tried it again due to some strange network probs where I seemed to be getting file xfer speeds as low as 200K/s. I tried the bench script, and its half broken now -- because I can no longer get anything back from the zero device on my server via the network. Locally, I can do 'dd' from /dev/zero (or the zero file) and it takes a few seconds and gave about 800MB/s. So seemed to have been working fine, but remotely -- still nada... reads 0 bytes from /dev/zero and about 300MB/s write speed. Can anyone think of anything that might have changed in cygwin such that it would know the remote device is a "/dev/zero". Wondered if the 'dd' prog might have changed, but just realize it did same with 'cat' as well. Anyway -- I'm a bit stumped as to possible causes... The writing to a remote /dev/null part is still working, so not sure why one would change and not the other. If anyone can think of anything, please let me know -- I'm also gonna ping the samba list and maybe my distro list Thanks! -linda