On Jun 29 12:59, Warren Young wrote: > I scp'd a 1.6 GB file back and forth to a Linux server over GigE to a > fast new RAID-10. I tested 1.7.0-50 and 20090629. > > Results: > > On a 32-bit XP box, 1.7.0-50 gives about 15 MByte/sec for both upload > and download. (This box can't really hit GigE speeds due to crappy > cabling and a low-quality switch.) On switching to the snapshot, the > download speed is about the same, but upload is cut to 4-5 MB/sec. > > On a 64-bit Vista box, 1.7.0-50 gives inconsistent behavior. Download > behaves as it should: ~45 MB/sec here, due to better switch and cabling. > But, uploading with scp gives the reported behavior: the scp status > fills out to 100% very fast but then scp doesn't finish running for > quite a while. It's like it's buffering a big fraction of the 1.6 GB, > which isn't impossible, since this box has 12 GB of RAM. (Core i7, > DDR3, wheee!) > > After switching to the snapshot on that Vista-64 box, the scp progress > display becomes useful, growing steadily as scp runs. Unfortunately, my > upload speed is down to around 5 MB/sec here, just as on the XP box. > > A different non-Cygwin scp client I have here can manage much faster > transfer speeds, so I can rule out disk and network bottlenecks. The > slowdowns are in Cygwin itself or the Cygwin scp port. > > I can rule out a problem in the general network I/O handling: changing > the DLL doesn't seem to affect ttcp results materially. It's either scp > or the way scp uses cygwin1.dll.
I just had a look into this and I think I found a way to raise the outbound transfer rates somewhat. The outbound speed is always slower than the inbound speed, no matter what I try. However, I'm now at a point where it might be more acceptable. One of my test machines, a 2K8 32 bit box has the following scp transfer rates under 1.5.25: inbound: 17.2 MB/s outbound: 3.5 MB/s With the latest snapshot: inbound: 21.5 MB/s outbound: 4.2 MB/s With the latest from CVS: inbound: 21.5 MB/s outbound: 11.5 MB/s What's still not clear is why the ssh process takes so much CPU. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- 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
