On Apr 13, 2013 11:57 PM, "Tamer Higazi" <th9...@googlemail.com> wrote: > > Am 13.04.2013 18:24, schrieb Pandu Poluan: > > > > On Apr 13, 2013 8:29 PM, "Tamer Higazi" <th9...@googlemail.com > > <mailto:th9...@googlemail.com>> wrote: > >> > >> Hi Dale! > >> > >> > >> Am 13.04.2013 13:54, schrieb Dale: > >> > Pandu Poluan wrote: > >> >> > >> >> > >> >> I myself prefer AMD CPUs to Intel ones. > >> >> > >> >> Intel has this habit of 'segmenting' their processor features. E.g., > >> >> Intel VT-x (Intel's buggy implementation of AMD-V) is not available > >> >> across the board. > >> > >> What is VT-x ???? > >> > > > > you really should learn to use Google... > > > > In short: VT-x is Intel's version of AMD-V. > > > > What is AMD-V? It's a feature of AMD CPUs that *greatly* assist > > virtualization. > > > > It's not just VT-x, there are a *lot* of features that Intel may or may > > not provide on a certain model. > > > >> And also all the time, Intel promotes for their "Hiperthreading" > >> support, as well Intel swears on their "QuickPath" system they have > >> developed and should release the FSB which is stil being used at AMD, > > > > Incorrect. AMD uses HyperTransport for a loooong time. QuickPath is just > > Intel's version of HyperTransport. > > > > As to Hyperthreading... it was technology from Pentium 4 actually, > > originally called "NetBurst", it splits a core into two virtual cores, > > leveraging Intel's long pipeline. There are benefits, but also drawbacks. > > > >> even when they mention that "MT (Megatransfer instead GHZ) for > >> describing their frontside bus speed.... > >> > >> so, it is in this case not only the CPU's speed, also the Speed the data > >> reaches the memory, and other components like the GPU of your graphics > >> device, no?! > >> > > > > Yes, and honestly, AMD was there first. IIRC, Intel still have some > > problems with cache coherency on multiple processor systems. AMD has no > > such problems; the HyperTransport technology used by AMD is perfectly > > capable of servicing NUMA Architecture. > > > >> > >> And what about Hyperthreading?! At the Gentoo make configuration guide, > >> the intel corei7 are fully supported. > >> > > > > The 'support' comes from gcc, and gcc fully supports AMD CPUs also. > > > >> There is being described, that if Intel corei 5 or 7 CPU's are used, I > >> could double the amount of cpu's for compiling > >> > >> MAKEOPTS="-j8" (for a quadcore core i5 / 7) because of it's > >> hyperthreading support. > >> > > > > As I wrote above, Intel's Hyperthreading splits each core into two > > virtual cores. Thus, if you know the number of physical cores *and* > > you've turned on Hyperthreading in the BIOS, you can (and should) double > > the number of jobs. > > > > That information is *not* due to Gentoo better supporting Intel, it's > > there because of Intel's complexity. > > > > AMD CPUs from the get-go already support a higher core density than > > Intel; they never need to split their cores into virtual cores. > > > >> > >> If one needs to leverage VT-x for virtualization > >> >> purposes, one must be double sure that the CPU one bought supports > > VT-x. > >> >> > >> >> All latest AMD CPUs (except the laptop versions) support all AMD > >> >> features. > >> > >> Where are the latest AMD CPU sets on Gentoo used at all ?! What about > >> the Intel's one?! And do they make a huge difference in this case?! > >> > > > > gcc -march=native will allow gcc to detect and leverage all features. > > > > I don't know which features are used where, except for AMD-V, which is > > heavily leveraged by virtualization (virtualbox or Xen, in my situation). > > > >> > >> If you can give me a deep technical answer, I would be very happy.... > >> > >> > >> The money is not what counts. It's the system stability. My AMD cpu was > >> veryyyyy loooong time ago an "AMD Athlon XP" which makde me a lots of > >> headache. > >> > > > > You're sooooooo out of date. > > > > Nowadays, AMD CPUs are at least as stable as Intel CPUs. > > > > Rgds, > > -- > > > > > > Hi Erick! > Thank you very much for your great description that makes my decision > easier. > > However, one last question.... > > > On a modern AMD machine, would I have to enable "hyperthreading" support > in the kernel as well, and should / must I double the cores at the > "MAKEOPTS" flag ?! >
One, I'm not Erick. Two, please don't top-post. Three, AMD has no concept of Hyperthreading. Just match -j to the number of cores your CPU provides, and that's it. As I wrote, an AMD Quad Core provides actual 4 cores. An "Intel Quad Core with Hyperthreading" actually provides only 2 physical cores, but then it performs some internal trickery so the OS sees a total of 4 cores. I much prefer having 4 actual cores than 4 virtual cores (only 2 actual cores); less chance of things messing up royally if I hit some edge cases where Hyperthreading falls flat on its face. Rgds, --
