On 2012-09-14 12:03, Michael Tokarev wrote: > On 14.09.2012 14:00, Jan Kiszka wrote: > [] >> The major difference in qemu-system-i386 vs. qemu-system-x86_64 is on >> the TCG side: We measured noticeable performance benefits when running >> 32/16 bit OSes against qemu-system-i386 vs. using qemu-system-x86_64. I >> don't have numbers at hand, but colleagues decided to use the 32-bit >> version for that reason (when no KVM is available). > > Interesting. Maybe someone should look at the difference on TCG side > and merge interesting bits from i386 to x86_64... :)
I suppose the difference - for our use cases at least - lies in the different register and address sizes. Maybe there is room for more runtime optimizations, we never looked in that details as -i386 still works fine. And, if you are on 32-bit host (see below) - but we aren't, qemu-system-x86_64 hurts even more. > > The thing is: x86_64 becomes the only x86 platform these days, or at > least the MAIN platform. I know, and I'm telling everyone. Still, too many crazy people keep on installing 32-bit distros or even 32-bit kernels. Maybe x64-32 will improve this. > > Thank you for the clarification -- very useful information indeed! > > /mjt > You are welcome. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux
