Hi Viraj,
You can use the attached file to get the DMM optimimzation that
Ramesh is referring to.
The location of this file is mpu_driver\src\wmd\omap\3430
Thank you,
Best regards,
Hari
> -----Original Message-----
> From: linux-omap-owner@xxxxxxxxxxxxxxx
> [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Viraj
> Karandikar
> Sent: Monday, June 09, 2008 10:18 AM
> To: Gupta, Ramesh; linux-omap@xxxxxxxxxxxxxxx
> Subject: RE: Sharing buffers between ARM-DSP on OMAP3430 over Bridge
>
> Thanks Ramesh.
> I was reserving and mapping buffers "every time". This was
> not required.
> I modified the code to reserve and map a buffer only once and
> use the mapped address for future.
> This modification reduced the overhead.
>
> I have one more doubt.
> Does DSP use virtual-to-physical mapping for all the
> addresses it accesses (including DSP's local buffers)?
> Or it uses this mapping only to access shared buffers?
> Wont it be a big overhead if DSP accesses all the memories
> through virtual-to-physical mapping?
>
> Regards,
> Viraj
>
>
>
> -----Original Message-----
> From: Ramesh Gupta G [mailto:x0023949@xxxxxx]
> Sent: Monday, June 09, 2008 11:03 AM
> To: Viraj Karandikar; linux-omap-open-source@xxxxxxxxxxxxxx
> Subject: Re: Sharing buffers between ARM-DSP on OMAP3430 over Bridge
>
> Hi Vijay,
>
> ----- Original Message -----
> From: "Viraj Karandikar" <viraj.karandikar@xxxxxxxxxx>
> To: <linux-omap-open-source@xxxxxxxxxxxxxx>
> Sent: Saturday, June 07, 2008 3:45 PM
> Subject: Sharing buffers between ARM-DSP on OMAP3430 over Bridge
>
>
> >Hi all,
>
> >I am working on omap3430 using bridge. I am using Dynamically Mapped
> >Memory (DMM) method for sharing buffers.
>
> >For sending buffers to DSP I am doing calls to
> >DSPProcessor_ReserveMemory() and DSPProcessor_Map(). For these calls
> are
> >taking around 18ms (for 3-4MB buffers) which is not
> acceptable for the
> >application. I am not able to understand why it is taking so
> much time?
>
> Which version of bridge you are using?
> We have optimized the code for DSPProcessor_Map(), You can see
> significant
> change in the
> numbers with the latest code.
>
>
> >My understanding of DMM method is ->
>
>
> >- Use malloc() to allocate a buffer on ARM.
>
> >- Reserve required chunk of memory from DMM pool (using
> >DSPProcessor_ReserveMemory() )
>
> >- Translate this memory to ARM virtual address space in
> >DSPProcessor_Map() function.
>
> Actually DSPProcessor_Map() maps ARM physical addresses to DSP Virtual
> addresses.
>
> >- Send the reserved memory address to DSP.
>
>
>
> >Is this correct? I am confused about how exactly this happens.
>
> You are correct except above point about DSPProcessor_Map().
>
> >Also Ihave a doubt if the reserved memory address is from
> DSP physical
> address
> >space? Or is it from ARM virtual address space for DSP
> physical address
> >space?
>
> Reserved Memory is from DSP Virtual Address.
>
> >Is DMM method does copy from malloc'ed address to reserved
> >address in any way?
>
> Do you mean copying the contents? No copying is involved. Only mapping
> of
> addresses is performed.
>
>
> >It will be helpful if anybody put some light on this.
>
> Please let me know if you see any issues.
>
>
>
> >Regards,
>
> >Viraj
>
>
> Thanks & Regards
> Ramesh Gupta G
>
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Attachment:
tiomap.c
Description: tiomap.c
