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Problem in brief: I am unable to increase
HTTP/SSL connection rate, while my Apache server platform shows a huge (98%) CPU
slack. ---------------- I benchmark the performance of several
Linux/Open Source applications on Intel Architecture (IA32/x86) servers. In
this context, I am trying to measure the peak HTTP connection rate sustained
when SSL is enabled in Apache. A ‘connection’ in this benchmark
consists of: TCP Connect HTTP Connect GET_SSL(a
small file with a few bytes) HTTP
Disconnect TCP Disconnect My test server side test setup consists
of: (1) Intel 5300 Xeon (quad core) 2.67GHz,
dual socket platform (with Intel 5000P chipset) – i.e., an 8 way SMP
platform (2) Linux 2.6.13 (CentOS 4.1) (3) Apache 2.0.52 (4) OpenSSL 0.9.7e (5) Intel 82571 PCI Express Gigabit
Ethernet NIC My client side test set up consists of: IxIA L4-L7 network traffic generator that
is capable of generating upto ***-220 connections/sec-*** and emulate several
thousand simultaneous HTTP/SSL clients. (Aptixia XM12 test chassis with IxIA
Application Logic Module test card). The IxIA test module, when tested against
Windows 2000/IIS has measured up to ***-220 HTTPS connections per second-*** on
a 2.8GHz single CPU/single core Xeon platform. PROBLEM: When I test my Linux/Apache
server for the same HTTPS connection rate, my IxIA tester measures ***-at most
10 connections/sec-***, while my server shows at least a 98% CPU slack (as
measured using Linux TOP utility). I have played with various TCP connection/persistence/buffer
options, but with no improvement what so ever. Also, when I run the same test without
SSL, I get a huge connection rate of ***-40000 HTTP connections/sec-***. This
leads me to believe that the problem lies somewhere with the modSSL module
& not Apache itself, ...but I am totally clueless after probing OpenSSL
stack for several weeks. Some basic Ethereal analysis shows that the server is
issuing a TCP RESET for nearly almost all connection requests from the IxIA
(virtual) clients. NOTE: The client side test configuration
& load is identical for both Windows 2000/IIS and Linux/Apache. I would greatly appreciate any known
insights into this issue. -
Hari <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< Hari Tadepalli Sr Staff Performance Engineer Intel Corporation Infrastructure Processor Division >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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