From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 12 Aug 1999 15:27:25 +1000 Message-Id: <199908120527.PAA30218@tango.anu.edu.au> From: Paul Mackerras To: dje@watson.ibm.com CC: rth@cygnus.com, Jes.Sorensen@cern.ch, Geert.Uytterhoeven@cs.kuleuven.ac.be, linuxppc-dev@lists.linuxppc.org, linux-fbdev@vuser.vu.union.edu In-reply-to: <9908120516.AA43198@marc.watson.ibm.com> (message from David Edelsohn on Thu, 12 Aug 1999 01:16:14 -0400) Subject: Re: [linux-fbdev] Re: readl() and friends and eieio on PPC Reply-to: Paul.Mackerras@cs.anu.edu.au References: <9908120516.AA43198@marc.watson.ibm.com> Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: David Edelsohn wrote: > Is your assumption that you want to provide the infrastructure to > write high-performance device drivers or to write device drivers that > don't require as much expertise and knowledge to produce correct results? Interesting question. I guess I would be trying both to make it easy to write device drivers that work, and possible to write very high-performance device drivers. Particularly since the vast majority of drivers in Linux have been written for the i386 platform, which doesn't do pesky (;-) things like reordering reads and writes. In any case, as far as the question of using readl/writel in framebuffer code goes, and whether readl/writel should include the eieio, the measurements I did showed zero performance impact of having the eieio, in frame-buffer copy code at least. Paul. [[ This message was sent via the linuxppc-dev mailing list. Replies are ]] [[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]] [[ reply is of general interest. Please check http://lists.linuxppc.org/ ]] [[ and http://www.linuxppc.org/ for useful information before posting. ]]