Mail Archives: cygwin/2010/02/17/17:17:45
Hi again,
Still working on this one. When I rsync/ssh a big file to my server over the
local network (100Mbit/s) with the --bwlimit=1000 I only have a small CPU
load. SSH takes about 10% and rsync approximately 0-5%. In the end the
transfer speed usually is around the value I set in bwlimit.
When I transfer the same file to a remote machine, where the bandwidth is
limited to roughly 140KB/s and the bandwidth limit is set to something below
this value I get around the same values which I have on the local network,
SSH 10% and rsync somewhere between 0-5%.
If I change the bwlimit value to 150KB/s or higher the SSH load goes up to
70% and rsync to 30% fully consuming my CPU.
I think the problem is pretty clear now. Does anybody have an idea, what the
next step could be to the resolution of this ?
Regards,
Jan
-----Oorspronkelijk bericht-----
Van: Jan Alphenaar [mailto:jan DOT alphenaar AT dotcolour DOT com]
Verzonden: woensdag 17 februari 2010 12:27
Aan: 'cygwin AT cygwin DOT com'
Onderwerp: FW: Cygwin Rsync/SSH performance issue
Hi
At first this email was sent to the developers list, but I understood this
list is more appropriate.
Regards,
Jan
-----Oorspronkelijk bericht-----
Van: Jan Alphenaar [mailto:jan DOT alphenaar AT dotcolour DOT com]
Verzonden: woensdag 17 februari 2010 12:25
Aan: 'cygwin-developers AT cygwin DOT com'
Onderwerp: RE: Cygwin Rsync/SSH performance issue
Hi,
In an attempt to narrow this down a bit I installed a RedHat machine with
openssh-5.3p1 and rsync-3.0.7 (thus without cygwin) and did the same test as
below.
Transferring data, both up and downstream, are not giving me any CPU load.
Although there is a small version difference in the rsync versions, I would
conclude that this is somehow caused by the cygwin layer.
If anybody can have a look at it, I would really appreciate it. If there is
something I can do, please let me know.
Warm regards,
Jan
-----Oorspronkelijk bericht-----
Van: Jan Alphenaar [mailto:jan DOT alphenaar AT dotcolour DOT com]
Verzonden: dinsdag 16 februari 2010 16:46
Aan: 'cygwin-developers AT cygwin DOT com'
Onderwerp: RE: Cygwin Rsync/SSH performance issue
Hi again,
I did some more testing on this and figured out that rsync/ssh is only
taking the full cpu if the bandwidth allocated to the session exceeds the
true bandwidth available on the link.
For example, if the uplink is 128KB/s and I pass in the --bwlimit=24
parameter the cpu is around 0%. Even --bw-limit=126 does not take 100% cpu,
but --bwlimit=132 does.
Would this be because of packet loss on the link and packets have to be
retransmitted ? I will do a quick test tonight with rsync/ssh between two
linux boxes, see what that gives me.
Regards,
Jan
-----Oorspronkelijk bericht-----
Van: Jan Alphenaar [mailto:jan DOT alphenaar AT dotcolour DOT com]
Verzonden: dinsdag 16 februari 2010 11:34
Aan: 'cygwin-developers AT cygwin DOT com'
Onderwerp: Cygwin Rsync/SSH performance issue
Hi everybody,
I am using rsync/ssh to copy files from my computer to my server and
everything seems to function as expected, except performance.
During a file transfer on my home computer (Intel I7) there is not a
noticeable CPU load. But on other (older) machines the rsync/ssh transfer
consumes all CPU resources on the sending side. I noticed there are other
questions regarding this subject in the archives, but I could not find a
solution for this. Also throttling the bandwidth to a lower value is not
helping to reduce the CPU load.
I am using quite a basic command to sync my files:
rsync -e ssh * <user>@<server>:/data
The versions of the software I am using are:
Cygwin: 1.7.1-1
ssh: OpenSSH_5.3p1
rsync: 3.0.6
OS: WinXP
Was anybody able to resolve this ?
Any help is greatly appreciated.
Warm regards,
Jan
--
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
- Raw text -