Hi Dan.

Thanks for your reply.

I've read the Microsoft document + information on the curl fix but they both seem to refer to sending data rather than receiving data.

However, as a test I added the TcpAckFrequencyRegistry setting to my Windows 7 VM that is performing the download (not the server). After a restart the file downloaded in approx. 9 seconds which is roughly what I expect. I also tested removing the registry setting and then restarting. As expected, performance dropped back to what it was previously.

so... It does seem that the problem has something to do with the TCP ACK on the client side rather than the server side so I guess this is a different problem to the one that was fixed. I've also ran a couple of tests with one of our applications that uses libcurl to perform downloads and it suffers from this problem so it isn't specific to the command line tools.

As I mentioned in my original email other applications running on the same computer download the file at the correct speed so there does appear to be an issue with libcurl.

The obvious work around is to change the Registry but it is a system wide change which might have other implications. Our app that uses libcurl is also deployed in environments where changing the Registry would not be feasible.

Regards,
Kevin.

On Tuesday, 21 January 2014, 20:20, Dan Fandrich <dan_at_coneharvesters.com> wrote:
On Tue, Jan 21, 2014 at 03:19:12PM +0000, Kev wrote:
> We are seeing very slow performance when using Curl under MS-Windows. The problem seems to be when we are downloading files via HTTP GET requests. For example, downloading an 80MB file across our network gives the following results:1. Mac running curl command line tool 7.24.0 between 9 & 20 seconds
> 2. MS-Windows running curl command line tool 7.34.0 between 142 & 167 seconds
>
> We have duplicated this on VMs running Windows 7 and Windows 2008 Server. To rule-out it being a general networking issue on the VMs we have also timed how long it takes to download the files using IE and wfetch. Both of these applications downloaded the file at a similar performance to the Mac.
>
> The command line we have performed the test with is nothing special:
>
> curl "http://x.x.x.x/myfileurl" > curloutput.txt
>
>
> Do you need any additional information to investigate this?

The Microsoft KB http://support.microsoft.com/kb/823764 was brought up as
a possible problem in http://curl.haxx.se/mail/lib-2013-02/0009.html and commit
43e045fc was added to 7.30.0 to fix it. Do any of the other workaround
mentioned there help in you case, or is this a different issue?

>>> Dan

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Received on 2014-01-22