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Re: Call for TESTING (was Re: [1.7.0-50] scp progress counter flies through first 175 MB or so)


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.

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