On Wednesday 19 October 2005 23:57, Nix wrote: > On Mon, 17 Oct 2005, [EMAIL PROTECTED] stated: > > On Sunday 16 October 2005 19:31, Nix wrote:
> > You may > > correct me (you know more about GCC), but I expect scheduling to make > > some difference. Btw, I still haven't done the tricks to make UML use > > host cpu features - it's still compiled with default GCC settings for > > this. > Not a killer: those of us who really care will have made GCC default anyway > by specifying --with-cpu or a target-specific triplet to GCC configure. Hmm, but we don't run all on Gentoo, and in the world it may make a difference. And anyway, there's no reason against this except "I keep forgetting to do it". > > Actually, for the host kernel (which uses arch=k8, see > > arch/i386/Makefile)) SSEx makes no difference (the kernel can't allow GCC > > to use FP on its own, as you probably know - the kernel must explicitly > > enable FP state saving, and even then there are strict rules on FP usage, > > for instance you must be atomic). > Well, actually, if you don't specify -ffreestanding Which we do. > , GCC can implement > large block moves by going via SSE or MMX regs. (How common this is I'm > not sure. Probably not very, especially for MMX.) Don't know for the rest, but the kernel uses SSE (I don't recall which features) for memset/memcpy/copy_*_user. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
