[zeromq-dev] Improving latency with eventfd

Pavol Malosek malosek at fastmq.com
Fri Jan 30 14:53:40 CET 2009

From: "Martin Sustrik" Sunday, January 18, 2009 9:28 AM

> If there is anybody out there with Linux kernel >= 2.6.22 and glibc >=
> 2.8 we would appreciate feedback about whether latency has improved on
> your system.


Here are average results from latency tests with 100000 msgs with size 1B on 
loopback interface.

2x Quad-Core AMD Opteron(tm) Processor 8356, 1150.000MHz
eventfd: 32.99us
socketpair: 37.72us

2x Intel(R) Xeon(R) CPU E5440, 2.83GHz
eventfd: 29.23us
socketpair: 29.90us

We have observed significant improvement on AMD platform where difference 
between eventfd and socketpair, which is used by default, is 4.73us (12.5%).
So from rev. 944 eventfd header and usability is checked during ./configure 
and if it is usable evendfd mechanism is used by 0MQ library ( There is no 
need to set CXXFLAGS to -DZMQ_HAVE_EVENTFD before compiling anymore).


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