From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: Date: Fri, 5 Dec 2008 10:32:58 -0800 From: "Russ Cox" To: "Fans of the OS Plan 9 from Bell Labs" <9fans@9fans.net> Subject: Re: [9fans] image/memimage speed In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <13426df10812042239pde2100dw696049def0160c4a@mail.gmail.com> <39cb2be32e592403f7336c6200cf56a3@quanstro.net> Topicbox-Message-UUID: 5b183bb0-ead4-11e9-9d60-3106f5b1d025 On Fri, Dec 5, 2008 at 10:27 AM, Russ Cox wrote: >> i don't think this is the case. if you recall from the original >> post, i have used the pat registers to set up memory types on >> a pcie card and i do see dramatic speedups for drawing to >> the screen. however, reading from the screen is just as slow >> as before. > > I think the problem of I think the problem is that when video card manufacturers optimize read bandwidth, they are working on the read bw of the video card's RPC-like interface, not the read bw from the video memory. To a first approximation, no one reads directly from video memory. Russ