TJ, If I am not mistaken i7 920 is 4 core (45nm technology) not 6 core (32nm technology). Regards, AF
--- In [email protected], Tomasz Janeczko <gro...@...> wrote: > > 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 > > > > > > > > >
