On Wed, Sep 28, 2011 at 02:25:43AM +0200, Torbjorn Granlund wrote: > Running Debian's vmlinux-2.6.32-5-4kc-malta under qemu-system-mips works > very well--the system is fast, and when it is idle the qemu-system-mips > process on the host system consumes insignificant CPU. (The same is > true for qemu-system-mipsel, using the correesponding 'el' Debian > kernel.) > > But running Debian's 64-bit kernel vmlinux-2.6.32-5-5kc-malta under > qemu-system-mips64 consumes 100% on the host system, whether the guest > is idle or busy. (And for qemu-system-mips64el, the same is true for the > corresponding 64-bit el kernel.) > > This cpu usage makes it somewhat inconvenient to let the qemu processes > stay running. Is there anything that can be done about the cpu usage? > Is it a Linux problem (say, that the 64-bit kernel fails to invoke some > clever system sleep instruction when in the idle loop), or is it a qemu > problem?
Hi, It could be any of them or both. You'll have to dig a bit deeper and see if WAIT insns are beeing issued and if QEMU is successfully decoding them etc. > Another issue I ran into what the sh4 qemu performance. It is much > worse than other qemu ports (except perhaps ppc64). What is the reason > behind that? (The idle thing works well for sh4, though.) IIRC, the SH has an MMU that is a bit problematic wrt performance in QEMU. Cheers
