In my libcurl program, I use CURLOPT_INTERFACE with an IP string
("172.16.0.100"). Originally, I thought the the poor performance when
using CURLOPT_INTERFACE was inherent in the way Linux implements IP
aliases. However, I noticed that every time I run my program modprobe's
are being run for the address and these are generally causing the poor
performance. The modprobe's are caused by the call to if2ip (and
subsequent ioctl I believe which spawns a modprobe from the kernel). If I
comment out if2ip, my performance problems go away. I'm not quite sure
what the correct solution to this problem would be, but possibly
attempting to detect whether to string passed to curl_easy_setopt is a ip
or interface or host. Even better, separate CURLOPT_INTERFACE into
CURLOPT_INTERFACE and CURLOPT_IP or somewhere along those lines.

BTW, the performance impact is significant (15 times slower in terms of
connections per second).

 
Avery Fay

Symantec Corporation
Office:
(781) 530-2489
eMail:
avery_fay_at_symantec.com

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Received on 2003-05-09