From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3e1162e60711160735i53f06dbete4b8c12e584412a3@mail.gmail.com> Date: Fri, 16 Nov 2007 07:35:14 -0800 From: "David Leimbach" To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu> Subject: Re: [9fans] Current status of amd64 port? In-Reply-To: <3e1162e60711160733p152bbbd5qbf29e1d52de650f4@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <3e1162e60711160641y40a8ec9ejde7d348cb417876c@mail.gmail.com> <3e1162e60711160733p152bbbd5qbf29e1d52de650f4@mail.gmail.com> Topicbox-Message-UUID: fd429cb6-ead2-11e9-9d60-3106f5b1d025 On Nov 16, 2007 7:33 AM, David Leimbach wrote: > > On Nov 16, 2007 6:46 AM, erik quanstrom wrote: > > > Per your second a), performance does often improve quite a bit with 2x > > > the general purpose registers. > > > > > > > do you have some specific numbers to back up this claim? > > > > - erik > > > > Not handy, but I used to build MPI applications on Opterons in 32bit > mode, then build them in 64bit mode, and nearly always get a > performance boost out of the 64bit. Which was the exact opposite that > I'd get on PPC 32 vs 64 bit. > > PPC's a different animal, using 32bit instructions even when in a > "64bit mode" (doesn't really have modes), some immediate memory loads > can use up to 5 instructions in assembly... I didn't look much deeper > than that. > > I know I'm not alone in this observation either. > > I'm sure I could google some results, but I can't currently produce > any of my own (unless I can get some time to do so on Leopard, since > it supports both). > > Dave > http://www.geekpatrol.ca/2006/09/32-bit-vs-64-bit-performance/