From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11063 invoked by alias); 9 Jul 2014 16:46:30 -0000 Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Received: (qmail 11050 invoked by uid 89); 9 Jul 2014 16:46:29 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=0.1 required=5.0 tests=AWL,BAYES_05,RCVD_IN_DNSWL_NONE,SPF_SOFTFAIL autolearn=no version=3.3.2 X-HELO: qmta06.emeryville.ca.mail.comcast.net Received: from qmta06.emeryville.ca.mail.comcast.net (HELO qmta06.emeryville.ca.mail.comcast.net) (76.96.30.56) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 09 Jul 2014 16:46:27 +0000 Received: from omta14.emeryville.ca.mail.comcast.net ([76.96.30.60]) by qmta06.emeryville.ca.mail.comcast.net with comcast id QETf1o0061HpZEsA6GmSHB; Wed, 09 Jul 2014 16:46:26 +0000 Received: from [10.1.5.114] ([216.34.91.132]) by omta14.emeryville.ca.mail.comcast.net with comcast id QGkG1o00W2rLPg88aGkKpa; Wed, 09 Jul 2014 16:44:24 +0000 Message-ID: <53BD7161.5030209@acm.org> Date: Wed, 09 Jul 2014 16:46:00 -0000 From: David Rothenberger User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: cygwin@cygwin.com Subject: Re: Severe performance degradation of writev References: <20140707101049.GI1803@calimero.vinschen.de> <20140707134137.GK1803@calimero.vinschen.de> In-Reply-To: <20140707134137.GK1803@calimero.vinschen.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Reply-To: cygwin@cygwin.com X-SW-Source: 2014-07/txt/msg00117.txt.bz2 Corinna Vinschen wrote: > On Jul 7 12:10, Corinna Vinschen wrote: >> On Jul 7 07:28, jojelino wrote: >>> 2008-07-27 Corinna Vinschen >>> >>> * fhandler_socket.cc (fhandler_socket::send_internal): Send >>> never more then 64K bytes at once. For blocking sockets, loop >>> until entire data has been sent or an error occurs. >>> (fhandler_socket::sendto): Drop code which sends on 64K bytes. >>> (fhandler_socket::sendmsg): Ditto. >>> >>> This commit added workaround for KB823764. but it has brought >>> another performance issue when writev sends <64k of data. >> >> That's why the code contains that FIXME comment. If you have a >> good idea for simple code to split a message into the least >> number of pieces to minimize the number of WsaSendTo calls... > > I took a stab at the code and I think the new version improves > writing multiple small buffers a lot. In my testing it still works > in other scenarios, too, but I would be very grateful if somebody > could have a critical look into my code changes as posted in > https://cygwin.com/ml/cygwin-cvs/2014-q3/msg00003.html > > I uploaded a new developer snapshot to > http://cygwin.com/snapshots/ Please give it a thorough try. FWIW, this snapshot fixed a recent performance degradation for me when doing ssh/rsync transfers within my local network at work. These transfers had run at about 25 MB/s but recently degraded to about 500 kB/s. The snapshot restored the original performance. -- David Rothenberger ---- daveroth@acm.org Issawi's Laws of Progress: The Course of Progress: Most things get steadily worse. The Path of Progress: A shortcut is the longest distance between two points. -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple