From: Hendrik Boom <hendrik@topoi.pooq.com>
To: libre-riscv-dev@lists.libre-riscv.org
Subject: Re: [libre-riscv-dev] Fall 2022 Interfaces
Date: Fri, 12 Jun 2020 10:06:51 -0400
Message-ID: <20200612140651.s724ovvshtjjziqo@topoi.pooq.com> (raw)
In-Reply-To: <CAPweEDxSRNtU2Y8AS2Xc+mCP7wEpDtCUJkRuJ9k3bk5VHb9jKw@mail.gmail.com>
On Fri, Jun 12, 2020 at 02:30:42PM +0100, Luke Kenneth Casson Leighton wrote:
> On Fri, Jun 12, 2020 at 1:38 PM Yehowshua <yimmanuel3@gatech.edu> wrote:
> >
> >
> > > that may not be enough to handle framebuffers as well as run an OS.
> > > framebuffers are scarily demanding of memory bandwidth and they absolutely
> > > MUST have total absolute top priority.
> >
> >
> > The OMI interface has 3200MT/s which is the same spec as DDR4.
>
> 3200 million transactions/sec, let's assume 8 bytes. that's 3200
> megabytes per second. 25 gigabit / 8 equals 3.125 so that fits with
> the math , there. one 25 gigabit lane provides 3200 million 8-bit
> transactions per second (3.125).
>
> 4k is 1200 megabytes per second: 37.5% *percent* of the total memory
> bandwidth consumed by a 4k 60fps framebuffer! and if people wanted
> 120 fps instead, that's now a staggering 75% of a single OMI interface
> dedicated to the framebuffer!
>
> bear in mind that that is *just* the framebuffer hardware. the CPU -
> the GPU - is contending for the exact same memory resource.
>
It's just possibe that we may not *need* 4k at 120 fps.
Certainly there are many potential applications for our chip that don't
need that kind of video.
-- hendrik
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Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 2:59 Yehowshua
2020-06-12 3:00 ` Yehowshua
2020-06-12 4:01 ` Jacob Lifshay
2020-06-12 4:33 ` Cole Poirier
2020-06-12 5:46 ` Yehowshua
2020-06-12 7:07 ` Yehowshua
2020-06-12 11:03 ` Luke Kenneth Casson Leighton
2020-06-12 11:21 ` Luke Kenneth Casson Leighton
2020-06-12 12:38 ` Yehowshua
2020-06-12 13:30 ` Luke Kenneth Casson Leighton
2020-06-12 14:06 ` Hendrik Boom [this message]
2020-06-12 14:23 ` Cole Poirier
2020-06-12 19:34 ` Yehowshua
2020-06-12 19:43 ` Yehowshua
2020-06-12 21:42 ` Luke Kenneth Casson Leighton
2020-06-12 23:17 ` Jacob Lifshay
2020-06-13 0:10 ` Luke Kenneth Casson Leighton
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