[parsec-users] branch intensive benchmark

Mahmood Naderan nt_mahmood at yahoo.com
Fri Jul 16 05:05:24 EDT 2010


Hi,
I have received them via maling list (patch_serial and patch_pthread). I will 
try to use them. Thanks for your tip.
 
// Naderan *Mahmood;




________________________________
From: "Fedorova, Julia" <Julia.Fedorova at intel.com>
To: PARSEC Users <parsec-users at lists.cs.princeton.edu>
Sent: Fri, July 16, 2010 11:36:51 AM
Subject: Re: [parsec-users] branch intensive benchmark


Hi Mahmood
 
I won’t be so certain on this. 
 
Recently I was able to speed up fluidanimate by ~ 20% improving code around 2 
mispredicted branches. 

(I’ve sent that patch to PARSEC list  – pls let me know if you want it)
 
The fix was not improving the quality of the prediction 
but rather avoiding the execution of the poorly predicted branches ,when it is 
possible, and a number of instructions around it. 

 
As a result – I got significant absolute decrease in number of mispredicted 
branches and some decrease in number of overall retired instructions. And as 
final result ~ 20% improvement of elapsed time. 

 
 
It looks like Figure 8 estimates Branch misprediction impact as 10% (for 
fluidanimate). 

But my estimations on Intel Core i7 – showed ~ 30%. 
And the fix I made kind of closer to my number. (while more analysis should be 
done on this)
 
So before the fix and even after – the branch misprediction was and is still 
glaring problem at fluidanimate. 

 
Hope this was useful.
 
Regards, Julia

________________________________

From:parsec-users-bounces at lists.cs.princeton.edu 
[mailto:parsec-users-bounces at lists.cs.princeton.edu] On Behalf Of Mahmood 
Naderan
Sent: Friday, July 16, 2010 10:32 AM
To: PARSEC Users
Subject: Re: [parsec-users] branch intensive benchmark
 
The only thing related to branch mispredict is Figure 8. From that I understand 
branch mis predict isn't a major bottleneck. Thanks,
 
// Naderan *Mahmood;
 
 

________________________________

From:Christian Bienia <cbienia at CS.Princeton.EDU>
To: PARSEC Users <parsec-users at lists.cs.princeton.edu>
Sent: Fri, July 16, 2010 12:54:24 AM
Subject: Re: [parsec-users] branch intensive benchmark
Hi Naderan,
 
I haven’t characterized the branch behavior of PARSEC myself, but Major 
Bhadauria did some work on single-thread characteristics. You might find some 
relevant information in his publication “Understanding PARSEC Performance on 
Contemporary CMPs[“
 
Best,
Chris
 
 
 
From:parsec-users-bounces at lists.cs.princeton.edu 
[mailto:parsec-users-bounces at lists.cs.princeton.edu] On Behalf Of Mahmood 
Naderan
Sent: Thursday, July 15, 2010 1:31 PM
To: PARSEC
Subject: [parsec-users] branch intensive benchmark
 
Hi,
Which benchmark is "branch instruction" intensive?
 
// Naderan *Mahmood;
 
 
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