Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <[email protected]> · Thu, 14 Nov 2019 08:38:27 -0800

On 11/14/19 8:05 AM, J. Lewis Muir via Tech-talk wrote:
> On 11/14, Mark Rivers via Tech-talk wrote:
>> So on Linux running the "curl" command via a call to system() is actually almost 3 times faster than calling either of the libraries directly.  This surprises me.
> 
> That makes no sense.

SFTP (which is based on SSH, not SSL/TLS) is quite a complicated protocol
with a lot of options.  Two slowdowns I've seen are lack of a reverse
DNS entry, and authentication fallback (notable krb5).

My first suggestion is to look at configuration options.  eg. it isn't
immediately clear to me whether libssh will read "/etc/ssh/ssh_config"
or "~/.ssh/config".

> There must be something different about how you're
> using libcurl vs. curl.  Have you tried curl's "--libcurl <file>"
> option?  I would try that.  Basically, take the curl command line that
> works, and then add the "--libcurl <file>" option to it, and it will
> emit C source code for a program using libcurl that does the same thing.
> Compare that with how you're using libcurl.
> 
> Lewis
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System