Date: Wed, 5 Mar 2014 15:43:09 -0800 From: Justin Hibbits <jhibbits@freebsd.org> To: Bruce Evans <brde@optusnet.com.au> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-arch@freebsd.org Subject: Re: newcons fb driver Message-ID: <CAHSQbTDxX=XPcKYmA-7pLa8n9xi2izKrJAEtuzonCU1X6jxadA@mail.gmail.com> In-Reply-To: <20140306013120.H1530@besplex.bde.org> References: <42130.1393829535@critter.freebsd.dk> <5314B2A2.3060100@pix.net> <CAHSQbTBTq6EKD_crn=rvbeUcAEBn7E%2B=U8wRHeqchazF1LhjwQ@mail.gmail.com> <60475.1393876211@critter.freebsd.dk> <20140304071445.Y3158@besplex.bde.org> <CAHSQbTB3FwMDo01LuWvd4zN%2BYHzbDSVHqfiYGeRCnb0iqCkBmA@mail.gmail.com> <20140305230458.L1053@besplex.bde.org> <20140306013120.H1530@besplex.bde.org>
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On Wed, Mar 5, 2014 at 7:02 AM, Bruce Evans <brde@optusnet.com.au> wrote: > On Thu, 6 Mar 2014, Bruce Evans wrote: > >> On Tue, 4 Mar 2014, Justin Hibbits wrote: >>> >>> Without some kind of optimization, newcons on powerpc is unacceptably >>> slow. >> >> >> How slow is that exactly? If the frame buffer speed is 50MB/S, then >> 16x8 characters with 256 colors can be written at 390K/S. This is >> acceptable. If the frame buffer is much slower than that, then it is >> too slow, at least without hardware scrolling. > > > I forgot to mention that u$ doesn't solve this problem in WinXP. The > speed is not too bad in normal mode (only about 30 times slower than > syscons - the scrolling speed is 30000 lines/second instead of 1000000). > But in safe mode, a simple graphics driver is used and it is horribly > slow. Safe mode with command prompt gives an MSDOS prompt in a > maximized terminal window, so the problem is very noticeable (the > scrolling speed is 4 lines per second = 12 seconds per screenful). > Apparently normal mode uses acceleration to be not very slow, but safe > mode is too simple to do that. The FreeBSD console driver needs to > be even simpler so that it works as a low level console. > > Bruce The ofwfb syscons driver is much faster than newcons, so a frame buffer can be made relatively fast (within reason). It's newcons that's slow, and my assumption currently is the byte-oriented writes instead of word size. - Justin
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