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On Saturday 29 Oct 2005 09:34, Robin Cornelius wrote: > Hi guys, > > How can i take advantage of an athlon 64 processor. > > >From what i can make out the Athlon 64 is a extended i386 instruction > > set so i presume there are a whole buch of 64 bit instructions avaiable. > So if i compile my kernel with the athlon 64 processor selected the > kernel can take advantage of the 64 bit instructions. Thats well and > good but is there much in the kernel that will benifit from 64 bit? > there are no floating point operations in kernel space, may be some data > transferers can be more efficient and in reduced clock cycles? You probably won't see any advantages from a 64-bit kernel. On non-x86 64-bit architectures, very few people use 64-bit kernels because there simply isn't much to be gained by doing so. That said, optimising for AMD 64 will ensure the kernel can make use of the available instructions, but the performance improvements are likely to be negligible. > > Its the apps and especialy number crunching/data processing that should > benifit the most. I can't see any debain athlon64 sources so i assume i > am stuck with i386 unless I want to compile everything (gentoo?) and i > quite like debian and how things run at the moment anyway. An unofficial stable release of Debian for AMD64 has been released, see: http://www.debian.org/ports/amd64/ There's also Ubuntu (www.ubuntu.com) based on the Debian sources, but it's really buggy on AMD64, presumably because there aren't enough people testing it. Things like video/audio compression and decompression, SETI@Home and similar apps will as you say benefit from being 64-bit, but compiling some applications as 64-bit will actually reduce their performance. If an app primarily works with small blocks of data, these blocks have to be padded to the register size of the architecture - so 32-bit on x86 and 64-bit on x86_64. So now you're working with 64-bit blocks of data instead of 32-bit blocks for no good reason, which naturally is more inefficient and reduces performance. See: http://www.redbooks.ibm.com/abstracts/tips0475.html?Open HTH, David. -- David Johnson www.david-web.co.uk - My Personal Website www.ethereye.org.uk - EtherEye Network Host Checker www.penguincomputing.co.uk - Need a Web Developer? -- The Mailing List for the Devon & Cornwall LUG Mail majordomo@xxxxxxxxxxxxx with "unsubscribe list" in the message body to unsubscribe. FAQ: www.dcglug.org.uk/linux_adm/list-faq.html