I checked the archives and the only thing that I see is that dloyer123 wrote a plugin using cuda and he saw significant improvement in his back testing. Have you tested AB with Cuda? Any plans to implement such technologies in AB? TIA
From: [email protected] [mailto:[email protected]] On Behalf Of Tomasz Janeczko Sent: Sunday, August 22, 2010 1:03 PM To: [email protected] Subject: Re: [amibroker] OT: mutlicore cpu Hello, CUDA was discussed before, check the archives. Best regards, Tomasz Janeczko amibroker.com On 2010-08-22 21:52, TA wrote: Thanks again. My last question. Have you tested AB to hand over some calculations to GPU (e.g., using CUDA)? Since GPU has its own FPU and memory. Sorry for all these layman question! I am really fascinated by all these stuff. TIA From: [email protected] [mailto:[email protected]] On Behalf Of Tomasz Janeczko Sent: Sunday, August 22, 2010 12:30 PM To: [email protected] Subject: Re: [amibroker] OT: mutlicore cpu Hello, "why you bought an i7 (6 core) cpu?" Several reasons - my previous computer was 4 year old and it was 2 core. Buying anything less than i7 would not give me any visible gain. In, although new machine is faster, in everyday tasks it makes little difference (especially with the fact that Windows and other softwares add bloat faster than hardware evolves.) As to technical reasons - among other things - to do actual tests. 4 years ago I have written portions of AFL engine using OpenMP (parallel library) to test actual, real-world performance of parallel (multi-core) code vs single-core on AMD Athlon64x2 (2core) Last year, I bought i7 to re-run those tests on latest hardware. The conclusion is the same, fine-grain parallelism (the one that OpenMP supports) with 3:1 memory to FPU ratio makes no sense performance-wise. You need much more FPU/CPU calcs per single memory access to make it worthwhile. With regards to buying new hardware: If you develop software, you need to have several platforms to test on to ensure smooth operation on every popular hardware. I am testing AmiBroker on everything starting from Intel Celeron 600MHz (10-year old notebook), AMD Athlon XP (single core), AMD Athlon64x2 (dual core), Intel Core 2 Duo (2 core), and ending with Intel i7 920 (6core). Best regards, Tomasz Janeczko amibroker.com On 2010-08-22 20:43, TA wrote: 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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