performance scalability of a multi-core

Ken Brownfield kb+varnish at
Thu Sep 10 18:32:46 CEST 2009

My weapon of choice there would be oprofile, run something like this  
under high load and/or when you have a lot of threads active:

opcontrol --init
# You'll want a debug kernel
# For example, the Ubuntu package is linux-image-debug-server
opcontrol --setup --vmlinux=/boot/vmlinux-2.6.24-server
opcontrol --reset ; opcontrol --start ; sleep 60 ; opcontrol --stop
opreport -r -l (with and without -l)

At the bottom you'll see the most costly calls and any obvious stand- 
outs.  My runs on Varnish show an interestingly high amount of  
timezone stuff in libc, but no real low-hanging fruit.

On Sep 10, 2009, at 1:22 AM, Václav Bílek wrote:

>> I guess my point is that certain use cases (some valid, some not,  
>> some
>> involving bad pthread libraries in distributions (lots of them out
>> there!))
> How can I identify if our pthread libraries are in trouble?

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