Hi!

First, thanks for the attention to my report and the immediate call for
particpation!

> Georg Lippitsch reported that he could reach twice the download performance
> with libcurl simply by upping CURL_MAX_WRITE_SIZE to 40960.

I have to clarify, and sorry that I didn't mention before:
My test was an upload, not a download!

Here are some details about what I found:
I'm using libcurl in an application to upload files to an ftps server.
Earlier, I used libcurl 7.18.0 compiled with MSVC8, and that worked.
Recently, I updated to MSVC9 SP1 and curl 7.19.6. Since that, I was not able
to upload more than about 90 kBytes/s. As stated, upping CURL_MAX_WRITE_SIZE
to 40960 fixed the problem, giving a speed of more than 200 kByte/s.

Everything on a mobile UMTS connection, using a HUAWEI E270 modem!

I'm of course aware that mobile internet connctions may vary speed
excessively, so I also tried uploads with another client (filezilla), and I
tried both versions of curl, and only the version with low
CURL_MAX_WRITE_SIZE had low speed. So it seems almost certainly to me that
upping the size increased the speed.

Of course, the most important thing now is confirming these tests. That won't
be easy, because I was only able to reproduce them with my mobile UMTS modem.
All other connections (LAN, ADSL) worked perfectly well.
AFAIK, mobile internet connections might have quite different timings and
buffer sizes than LANs, what might be an explanation.

So I would in particular invite people who have the same or a similar UMTS
modem to participate in this test!

Georg
Received on 2009-08-19