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Re: libssh2 optimization [was: Re: Windows users! Help us test upload performance tuning?]

From: Jan Ehrhardt via curl-library <>
Date: Thu, 30 Aug 2018 16:23:57 +0200

Jan Ehrhardt via curl-library (Sun, 26 Aug 2018 16:28:47 +0200):
>Daniel Jelinski via curl-library (Sun, 26 Aug 2018 09:09:58 +0200):
>>The patched version is CPU-bound on lower latencies; when the latency
>>goes higher, SSH window becomes the limiting factor. I read that HPN
>>SSH should do better on high latency links, didn't try it out.
>A lot of PR's for HPN-SSH came from @allanjude. Interesting stuff:

In May 2017 Allan Jude posted a new HPN patch here:

> In my benchmarks with 100ms of latency (from dummynet) is increases SSH
> send throughput from 1 megabyte/sec to 225 megabytes/sec provided a
> large enough socket buffer.

I cannot reproduce that. I applied a modified version of this patch to
OpenSSH-portable for Windows:

For anyone that wants to try it:

The scripting is done with Expect for Windows:

Received on 2018-08-30