Hi Ravi

The Intel HT actually has its own resources except few places like execution 
units and other resources in the pipeline, hence there are many factors play 
here for the performance of the application with and without HT feature. In 
simple words, even when you turned on the HT, and use only one of the HT, then 
the performance will be more or less be similar to the core with HT turned off. 
Also assume that if you are running same piece of code in both the HTs, but it 
doesn't have lots have contention on the common resource (you can figure out 
this using vTune profiling), then there will be very marginal performance 
difference between HT turned ON Vs OFF.

Regards
Kannan Babu

-----Original Message-----
From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Ravi Kumar Iyer
Sent: Tuesday, October 7, 2014 8:59 AM
To: dev at dpdk.org
Subject: [dpdk-dev] Queries related to Hyperthreading

hello Intel Gurus,

I have some queries related to intel HT technology. I am running an intel dpdk 
application and  trying to benchmark as well as optimize the same. As of now it 
is a single threaded application and would like to keep it like that for now. I 
am running it on an intel sandy bridge arch processor with HT on. Now to 
increase the performance I have disabled HT, but am still getting the same 
performance[ just a marginal improvement]. Now as per our understanding so far 
wrt HT, two Hardware threads share the same physical core. Now if we switch off 
HT[from bios] shouldn't just one hardware Thread get hold of the complete CPU 
core.  The application is heavily compute oriented and as such minimal memory 
access or any IO operations. Appreciate any insight on this.


thanks
ravi


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