2009/9/10 Rames <[email protected]>: > > The -march=armv7-a indeed solved all my problems. Thank you > very much for all you answers. > > So I eventually get a score around 94 for the v8 (version 3) tests > with v8 on an OMAP3530 (Cortex A8 600MHz). > I previously got a score around 800 on a 800Mhz Intel processor. > > The score gap is amazing for only 200MHz difference. I have not > compared v8 arm and ia32 code. Do you know if this gap results from a > better code optimization and/or better native code usage (I see a lot > of posts relative to ARM work on the v8-dev group so I guess the ARM > work is not yet to the level of the ia32's) or if the x86 architecture > merely have a more efficient Instruction Set or architecture?
The code generator for ARM is not as advanced as the one for Intel. My very rough guess is that the score on the V8 benchmark suite could be almost doubled if the code generator were as advanced on ARM. The tricky bit is to speed up the running code without slowing down compilation, which can be a big factor in page load time on slow devices. Looking at raw MHz can be misleading. The Cortex A8 design in the BeagleBoard is an in-order design, whereas the Cortex A9 ARM chip will be a "multi-issue superscalar, out-of-order, speculating 8-stage pipeline" according to ARM's white paper. This can make quite a difference. The in-order Atom is said by Wikipedia to have half the performance of the out-of-order low end Celerons with around the same Mhz. Apart from the MHz, the speed of the memory subsystem can be very important. This is partly a property of the CPU core itself, but to a larger extent a property of the second level cache size and speed as well as the speed of the external RAM interface. There are many tradeoffs here in system design to do with cost, space and power use. It's fair to say that V8 (and browser) performance is very dependent on the memory subsystem. -- Erik Corry, Software Engineer Google Denmark ApS. CVR nr. 28 86 69 84 c/o Philip & Partners, 7 Vognmagergade, P.O. Box 2227, DK-1018 Copenhagen K, Denmark. --~--~---------~--~----~------------~-------~--~----~ v8-users mailing list [email protected] http://groups.google.com/group/v8-users -~----------~----~----~----~------~----~------~--~---
