Thanks for clarification. Would you mind sharing with us why you bought an
i7 (6 core) cpu? TIA

 

From: [email protected] [mailto:[email protected]] On Behalf
Of Tomasz Janeczko
Sent: Sunday, August 22, 2010 11:24 AM
To: [email protected]
Subject: Re: [amibroker] OT: mutlicore cpu

 

  

Hello,

Video creation software is completely different. They do a lot of math *per
pixel* (it means that lots of FPU operations are needed for single pixel),
for example many algorithms use 8x8 pixel blocks 64*(4 bytes per pixel)=
256bytes and do complex transform such as cosine transform. It means that
lots of FPU instructions are done on very small blocks of memory that
completely fit on Level 1 CPU cache and thus they are not able to saturate
memory bandwidth. They literally do dozens of FPU ops per single RAM access.
In fact they barely need to touch RAM at all. It is completely opposite to
how AFL works, where there is usually 3 times more memory accesses (2 reads
+ one write) than FPU operations. 

And yes I do know what processors are on the market. In fact I do have i7 (6
core) (I am writing this post using it). 

The only reason for multi threading in case of AFL would be not speed but
asynchronous/parallel execution (ability to run AFL that takes long time in
parallel
(without blocking) other AFLs).

Best regards,
Tomasz Janeczko
amibroker.com

On 2010-08-22 01:19, TA wrote: 

TJ

 

On many occasions you have written that the reason that you have not
implement multicore usage in AB is that single symbol  data saturates the
on-die cache and memory bandwidth. The tests that I have seen for video
creation shows the apps that take advantage of multicore processes finish
the tasks faster. Do you know why that is? Do you know why AMD & Intel are
creating six core cpus (soon 8 core cpus)?TIA 



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