From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailout.easymail.ca (mailout.easymail.ca [64.68.200.34]) by sourceware.org (Postfix) with ESMTPS id D277A3857C67 for ; Wed, 25 Aug 2021 18:52:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D277A3857C67 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=house.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=house.org Received: from localhost (localhost [127.0.0.1]) by mailout.easymail.ca (Postfix) with ESMTP id 4A21410DAF2 for ; Wed, 25 Aug 2021 18:52:04 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at emo02-pco.easydns.vpn Received: from mailout.easymail.ca ([127.0.0.1]) by localhost (emo02-pco.easydns.vpn [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZXzyUj9mp6qU for ; Wed, 25 Aug 2021 18:52:00 +0000 (UTC) Received: from tringa.house.org (S0106bcee7b974edc.gv.shawcable.net [24.108.53.141]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mailout.easymail.ca (Postfix) with ESMTPSA id C595310DAEB for ; Wed, 25 Aug 2021 18:51:59 +0000 (UTC) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\)) Subject: Re: cygrunsrv + sshd + rsync = 20 times too slow -- throttled? From: Chris Roehrig In-Reply-To: Date: Wed, 25 Aug 2021 11:51:58 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: <41A583E1-C8E7-42AB-9F24-EEC33A41EC60@house.org> <20210825201845.07b6400b79dc5558a7761efe@nifty.ne.jp> To: "cygwin@cygwin.com" X-Mailer: Apple Mail (2.1499) X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Wed, 25 Aug 2021 18:52:15 -0000 It looks like there was a previous (2013) patch and attempt to add a = pipe_nooverlap CYGWIN option that was rejected by the maintainers: = https://stackoverflow.com/questions/10385424/good-alternatives-to-cygwin-c= ygwin-doesnt-support-natively-support-win32-app Is this something that can be revisited? It seems to be affecting = pure-UNIX situations (in my case) which is Cygwin's core audience. - Chris On Wed Aug 25 2021, at 11:18 AM, Chris Roehrig = wrote: > On Wed Aug 25 2021, at 10:52 AM, Ken Brown via Cygwin = wrote: >> A couple years ago I had an idea for changing the pipe implementation = to avoid overlapped I/O: >>=20 >> https://cygwin.com/pipermail/cygwin-patches/2019q2/009393.html >> https://cygwin.com/pipermail/cygwin-patches/2019q2/009423.html >>=20 >> I never followed up on it. But if you think it might help with this = problem, I could dust it off and try to finish it. >>=20 >> Ken >=20 > I'm not familiar enough with the innards of rsync, sshd or cygwin to = know how this would work. > Is it possible to have a new CYGWIN environment option to switch the = pipe behaviour without requiring changes to the ssh or rsync source code = (and without breaking any existing stuff)? >=20 > - Chris >=20 >=20 >=20 >> On 8/25/2021 7:18 AM, Takashi Yano via Cygwin wrote: >>> On Tue, 24 Aug 2021 12:49:52 -0700 >>> Chris Roehrig wrote: >>>> I have a network of Windows, Linux and Mac machines and I use rsync = to synchronize various directories between them. >>>>=20 >>>> I'm trying to figure out why my rsync transfers are so slow (<4 = MB/s) only when the remote endpoint is Cygwin rsync over sshd (with both = a Linux or Cygwin rsync client). In all other scenarios, I get the = full 100MB/s as expected from gigabit ethernet. This has been an = ongoing problem for me for a couple of years over several Windows and = Cygwin versions, and I'd like to try to fix it. >>>>=20 >>>> If I run rsync --daemon --no-detach under mintty in the foreground = on the remote Windows endpoint, I get the full 100 MB/s transfers, so = it seems like it has something to do with rsync.exe running in the = background under the cygrunsrv+sshd service (which was installed = normally using ssh-host-config). >>>>=20 >>>> If I do: >>>> pv /dev/zero | ssh $WINHOST "cat > /dev/null" >>>> or even >>>> pv /dev/urandom | ssh $WINHOST md5sum >>>> I also get the full 100 MB/s transfers, so it doesn't look like = sshd itself is being throttled by bandwidth or CPU. >>>>=20 >>>> The machines have less than 15% CPU utilization while transferring, = with each of the 4 cores less than 30%, so it doesn't look to be CPU = issue. >>>> In Task Manager, sshd.exe and rsync.exe seem to be running normally = using only few percent CPU, and show Power Throttling=3DDisabled, = Priority=3DNormal. Setting their Priority to High doesn't seem to = change things. >>>>=20 >>>> Looking in Resource Monitor on the remote endpoint, the network = usage is pretty much a flat horizontal line at about 18 Mbps (2.5 MB/s), = so it sure looks to me as if rsync is somehow being bandwidth-throttled=08= when run in the background under cygsshd. >>>>=20 >>>> It's almost as if rsync has an implicit --bwlimit override when it = is run from cygrunsrv+sshd (I've tried --bwlimit=3D0 on the client which = makes no difference). >>>>=20 >>>>=20 >>>> Any ideas? Not sure where to go from here. >>> In cygwin, just scp is very slow. >>> The transfer speed in my environment is as follows. >>> The tests were done with 100MB of test.dat file. >>> (1-1) =46rom cygwin-PC, >>> [yano@cygwin-PC ~]$ scp test.dat yano@linux-server:. >>> yano@linux-server's password: >>> test.dat 100% 100MB 4.0MB/s = 00:24 >>> [yano@cygwin-PC ~]$ scp yano@linux-server:test.dat . >>> yano@linux-server's password: >>> test.dat 100% 100MB 8.0MB/s = 00:12 >>> (1-2) =46rom linux-server, >>> yano@linux-server:~$ scp yano@cygwin-PC:test.dat . >>> yano@cygwin-PC's password: >>> test.dat 100% 100MB 4.0MB/s = 00:24 >>> yano@linux-server:~$ scp test.dat yano@cygwin-PC:. >>> yano@cygwin-PC's password: >>> test.dat 100% 100MB 4.1MB/s = 00:24 >>> I looked into this problem, and noticed that this is caused >>> by cygwin pipe implementation. Pipe in cygwin is configured >>> with FILE_FLAG_OVERLAPPED. >>> If the pipe is configured without FILE_FLAG_OVERLAPPED, >>> the transfer speed is much improved as follows. >>> (2-1) =46rom cygwin-PC, >>> [yano@cygwin-PC ~]$ scp test.dat yano@linux-server:. >>> yano@linux-server's password: >>> test.dat 100% 100MB 85.5MB/s = 00:01 >>> [yano@cygwin-PC ~]$ scp yano@linux-server:test.dat . >>> yano@linux-server's password: >>> test.dat 100% 100MB 69.7MB/s = 00:01 >>> (2-2) =46rom linux-server, >>> yano@linux-server:~$ scp yano@cygwin-PC:test.dat . >>> yano@cygwin-PC's password: >>> test.dat 100% 100MB 80.1MB/s = 00:01 >>> yano@linux-server:~$ scp test.dat yano@cygwin-PC:. >>> yano@cygwin-PC's password: >>> test.dat 100% 100MB 57.7MB/s = 00:01 >>> I am not sure why this happens and how to fix this. >>=20 >>=20 >>=20 >> --=20 >> Problem reports: https://cygwin.com/problems.html >> FAQ: https://cygwin.com/faq/ >> Documentation: https://cygwin.com/docs.html >> Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple >=20 >=20 > --=20 > Problem reports: https://cygwin.com/problems.html > FAQ: https://cygwin.com/faq/ > Documentation: https://cygwin.com/docs.html > Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple