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Re: [openrisc] Cache Line Fill

To: <openrisc@opencores.org>, <mphan@nimbuswireless.com>
Subject: Re: [openrisc] Cache Line Fill
From: "Damjan Lampret" <lampret@opencores.org>
Date: Tue, 8 Jul 2003 17:17:42 -0700
References: <200307031817.h63IHl2Y002419@www.opencores.org>
Reply-To: openrisc@opencores.org
Sender: owner-openrisc@opencores.org
Michael,

you can check out or1k/or1200 (or or1k/orp/ ...) with the following branch
tag: branch_qmem

Make sure you have among other or1200 rtl files also file or1200_qmem_top.v,
this is where the embedded memory sits. (I had some problems creating branch
so please check that you have this file)

Then go to or1200_defines.v and enable OR1200_QMEM_IMPLEMENTED.

regards,
Damjan

----- Original Message -----
From: <mphan01@earthlink.net>
To: <mphan@nimbuswireless.com>; <openrisc@opencores.org>
Sent: Thursday, July 03, 2003 11:17 AM
Subject: RE: [openrisc] Cache Line Fill


> Hi Damjan,
>
> Please let me know if you already checked in the new data base for "I
> RAM replacement for I cache".
> I hope you did have a chance to do the final testing.
>
> Thanks
>
> Michael Phan
>
>
>
> ----- Original Message -----
> From: "Michael Phan" <mphan@n... >
> To: <openrisc@o... >
> Date: Thu, 26 Jun 2003 14:41:17 -0700
> Subject: RE: [openrisc] Cache Line Fill
>
> >
> >
> > Sound good to me.
> >
> > Thanks
> >
> > Michael Phan
> >
> >
> > -----Original Message-----
> > From: owner-openrisc@o...
> > [mailto:owner-openrisc@o... ]On Behalf Of Damjan Lampret
> > Sent: Thursday, June 26, 2003 11:37 PM
> > To: Openrisc@O...
> > Subject: Re: [openrisc] Cache Line Fill
> >
> >
> > Hi Michael,
> >
> > yes I'm back. Thanks.
> >
> > I'm doing some final testing so I'm sure I don't check-in some
> > garbage. I'll
> > check-in tomorrow evening or saturday (depending when I'm done
> with
> > testing).
> >
> > regards,
> > Damjan
> >
> > ----- Original Message -----
> > From: <mphan@n... >
> > To: <lampret@o... >; <openrisc@o... >
> > Sent: Thursday, June 26, 2003 11:51 AM
> > Subject: Re: [openrisc] Cache Line Fill
> >
> >
> > > Hi Damjan,
> > >
> > > I hope you are back from travelling and had a nice one.
> > > Did you check in the changes for "I RAM replacement for I
> > cache" yet?
> > > I am waiting to test it out.
> > >
> > > Thanks
> > > Michael Phan
> > >
> > >
> > > ----- Original Message -----
> > > From: "Damjan Lampret" <lampret@o... >
> > > To: <mphan@n... >,
> > > <openrisc@o... >
> > > Date: Sat, 7 Jun 2003 00:47:12 -0700
> > > Subject: Re: [openrisc] Cache Line Fill
> > >
> > > >
> > > >
> > > > Michael,
> > > >
> > > > I assume you mean the I RAM replacement for I cache? Not
> > yet, for
> > > > the moment
> > > > you can use RAM connected to iwb and I'll commit the
> > changes to the
> > > > cvs next
> > > > weekend (I'm travelling this weekend until next weekend).
> > > >
> > > > regards,
> > > > Damjan
> > > >
> > > > ----- Original Message -----
> > > > From: <mphan@n... >
> > > > To: <mphan@n... >;
> > > > <openrisc@o... >
> > > > Sent: Friday, June 06, 2003 11:11 AM
> > > > Subject: Re: [openrisc] Cache Line Fill
> > > >
> > > >
> > > > >
> > > > > HI Damjan,
> > > > >
> > > > > Just want to touch base with you on this project,
> > "instruction
> > > > execution
> > > > > with 0 wait state", did yo have a chane to put the
> > changes
> > > > into the
> > > > > CVS so we can download and try them out.
> > > > >
> > > > > Thanks in advance
> > > > > Michael Phan
> > > > >
> > > > >
> > > > > ----- Original Message -----
> > > > > From: mphan@n...
> > > > > To: lampret@o... , openrisc@o...
> > > > > Date: Tue, 6 May 2003 17:57:54 -0100
> > > > > Subject: Re: [openrisc] Cache Line Fill
> > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > Hi Damjan,
> > > > > >
> > > > > > Your feedbacks are so precious and helpful to
> > our
> > > > project. Exactly,
> > > > > > we
> > > > > > don't need to use MMU and want to replace the
> > cache with
> > > > fixed
> > > > > > memory for instruction execution with 0 wait
> > state. So
> > > > please put
> > > > > > your
> > > > > > changes in the CVS at your convenience so we
> > can try it
> > > > out and
> > > > > > measure the performance improvement. Our
> > project needs
> > > > about 512
> > > > > KB
> > > > > > for the cache.
> > > > > >
> > > > > > Thousand thanks
> > > > > > Michael Phan
> > > > > >
> > > > > >
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > From: "Damjan Lampret" <lampret@o... >
> > > > > > To: <openrisc@o... >
> > > > > > Date: Mon, 5 May 2003 21:21:38 -0700
> > > > > > Subject: Re: [openrisc] Cache Line Fill
> > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > > From: <mphan@n... >
> > > > > > > To: <openrisc@o... >
> > > > > > > Sent: Thursday, May 01, 2003 3:36 PM
> > > > > > > Subject: [openrisc] Cache Line Fill
> > > > > > >
> > > > > > >
> > > > > > > > Hi Damjan.
> > > > > > > >
> > > > > > > > In the current design of orp_soc,
> > with
> > > > > > or1200_registered_ouput
> > > > > > > > supported, a cache line fill takes 8
> > clocks
> > > > (2-2-2-2) to
> > > > > > fetch
> > > > > > > 4 DWORDs
> > > > > > > > from the SRAM/FLASH. And a single
> > DWORD fetch
> > > > takes 3
> > > > > > clocks
> > > > > > > > (including one idle cycle of wb_cyc_o
> > > > deasserted).
> > > > > > > >
> > > > > > > > If we have a very fast internal SRAM,
> > is it
> > > > possible to
> > > > > > do a
> > > > > > > cache line
> > > > > > > fill
> > > > > > > > with 4/5 clocks (1/2-1-1-1) by
> > changing the
> > > > wb_stb logic
> > > > > > in
> > > > > > > the
> > > > > > > > or1200_wb_biu.v and do a single DWORD
> > fetch
> > > > with 2
> > > > > > clocks.
> > > > > > >
> > > > > > > OR1200 is it is has been used in SoC
> > projects much
> > > > more
> > > > > > complxed
> > > > > > > than
> > > > > > > orp_soc. In all these projects the memory
> > subsystem
> > > > takes more
> > > > > > than
> > > > > > > 1/2-1-1-1. So the current 2-2-2-2 was fast
> > enough
> > > > for all
> > > > > > SoCs. If
> > > > > > > you
> > > > > > > however have faster memory subsystem than
> > > > modification of
> > > > > > > or1200_wb_biu and
> > > > > > > possibly IC/DC state machines will be
> > needed.
> > > > > > >
> > > > > > > >
> > > > > > > > My next question is can we increase
> > to cache
> > > > size to 512
> > > > > > kB to
> > > > > > > reside
> > > > > > > > the whole firmware and execute
> > instructions
> > > > from it with
> > > > > > 0
> > > > > > > wait state.
> > > > > > > >
> > > > > > >
> > > > > > > If you want to use MMUs, then no. This is
> > because
> > > > MMU's page
> > > > > > > translation is
> > > > > > > done at the same time as cache access -
> > virtual page
> > > > number is
> > > > > > > translated at
> > > > > > > the same time as cache hit is determined.
> > Since page
> > > > size is
> > > > > > 8KB,
> > > > > > > largest
> > > > > > > direct mapped cache can only be 8KB,
> > unless you use
> > > > several
> > > > > > ways,
> > > > > > > or unless
> > > > > > > cache access takes an additional clock
> > cycle (maybe
> > > > acceptable
> > > > > > for
> > > > > > > data
> > > > > > > accesses ?).
> > > > > > >
> > > > > > > Anyway if you don't need MMU, then your
> > caches sizes
> > > > are not
> > > > > > > limited. To
> > > > > > > increase cache size just add new IC/DC
> > configuration
> > > > (search
> > > > > > for
> > > > > > > "configuration" in or1200_defines.v and
> > when you
> > > > find IC and
> > > > > > DC
> > > > > > > configurations, just add a new size and
> > then enable
> > > > new
> > > > > > > configuration).
> > > > > > > Right now there are configurations for 4KB
> > and 8KB
> > > > caches.
> > > > > > >
> > > > > > > I'm working on one project where similar
> > to your
> > > > case all code
> > > > > > > needs to be
> > > > > > > accessible in 0 wait states. What I plan
> > to do is to
> > > > replaces
> > > > > > > caches with
> > > > > > > fixed memories - basically removing TAG
> > RAMs and
> > > > making sure
> > > > > > that
> > > > > > > the "hit"
> > > > > > > always happens when accessing certain
> > address range
> > > > and never
> > > > > > > happens when
> > > > > > > accesssing outside of that range. This
> > will
> > > > effectively
> > > > > > "change
> > > > > > > caches into
> > > > > > > fixed RAMs much like DSP RAMs or similar).
> > > > > > > If you want these changes, I can put them
> > into the
> > > > cvs with
> > > > > > > appropriate
> > > > > > > defines. But it will take a few days.
> > > > > > >
> > > > > > > regards,
> > > > > > > Damjan
> > > > > > >
> > > > > > > > Thanks
> > > > > > > >
> > > > > > > > Michael Phan
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> >
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