RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
Deos any one have any comments on by-passing the get_user_pages function for
the buffers that meets the following condition ? If not, this code will be
merged into dspbridge tree.
if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED) &&
+ (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE) &&
+ (~pgprot_val(vma->vm_page_prot) & L_PTE_BUFFERABLE)))
Basically, the logic to get the pages would be as follows instead of calling
get_user_pages.
static u32 user_va2pa(struct mm_struct *mm, u32 address)
{
pgd_t *pgd;
pmd_t *pmd;
pte_t *ptep, pte;
pgd = pgd_offset(mm, address);
if (!(pgd_none(*pgd) || pgd_bad(*pgd))) {
pmd = pmd_offset(pgd, address);
if (!(pmd_none(*pmd) || pmd_bad(*pmd))) {
ptep = pte_offset_map(pmd, address);
if (ptep) {
pte = *ptep;
if (pte_present(pte))
return pte & PAGE_MASK;
}
}
}
return 0;
}
Thank you,
Best regards,
Hari
> -Original Message-
> From: linux-omap-ow...@vger.kernel.org [mailto:linux-omap-
> ow...@vger.kernel.org] On Behalf Of Kanigeri, Hari
> Sent: Thursday, June 11, 2009 12:24 PM
> To: Bagadia, Sripal; Hiroshi DOYU; Ramirez Luna, Omar
> Cc: felipe.contre...@gmail.com; ameya.pala...@nokia.com; Menon, Nishanth;
> linux-omap@vger.kernel.org
> Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
>
> Sripal,
>
> > Currently, display driver maps the video buffers to userspace with
> > VM_RESERVED flag and pgprot_writecombine(). We are considering changing
> > pgprot_writecombine() to pgprot_noncached() to eliminate the need of all
> > cache maintenance overheads for video buffers.
> >
> -- Is this change in the current LO kernel ?
>
> I agree there is an overhead of flushing the cache by calling
> get_user_pages function. But there is some additional stuff that this
> function does and I am afraid that by-passing this function call for a
> Buffer that has VM_RESERVED flag and the BUFFERABLBE flags might create
> issues.
>
> The only reason get_user_pages is not used for the buffer that has VM_IO
> flag set is get_user_pages fails if this flag is set for the buffer. I am
> not sure if it is safe to by-pass the get_user_pages function call for
> buffer that has VM_RESERVED flag set though.
>
> Thank you,
> Best regards,
> Hari
>
> > -Original Message-
> > From: Bagadia, Sripal
> > Sent: Thursday, June 11, 2009 11:24 AM
> > To: Hiroshi DOYU; Ramirez Luna, Omar
> > Cc: felipe.contre...@gmail.com; ameya.pala...@nokia.com; Menon,
> Nishanth;
> > Kanigeri, Hari; linux-omap@vger.kernel.org
> > Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> >
> > > Would it be possible to tell the case/path, where
> > L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
> >
> > Currently, display driver maps the video buffers to userspace with
> > VM_RESERVED flag and pgprot_writecombine(). We are considering changing
> > pgprot_writecombine() to pgprot_noncached() to eliminate the need of all
> > cache maintenance overheads for video buffers.
> >
> > Regarding Felipe's comment:
> > > L_PTE_BUFFERABLE is obsolete, isn't it? L_PTE_MT_BUFFERABLE should be
> > used instead.
> >
> > I was working on 2.6.27.10, and agree that this needs to be updated for
> > newer kernels.
> >
> >
> > Regards,
> > Sripal
> >
> > -----Original Message-
> > From: Hiroshi DOYU [mailto:hiroshi.d...@nokia.com]
> > Sent: Thursday, June 11, 2009 2:16 AM
> > To: Ramirez Luna, Omar
> > Cc: felipe.contre...@gmail.com; ameya.pala...@nokia.com; Menon,
> Nishanth;
> > Bagadia, Sripal; Kanigeri, Hari; linux-omap@vger.kernel.org
> > Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> >
> > From: Hiroshi DOYU
> > Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> > Date: Wed, 10 Jun 2009 10:25:39 +0300 (EEST)
> >
> > > From: "ext Ramirez Luna, Omar"
> > > Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> > > Date: Wed, 10 Jun 2009 01:18:29 +0200
> > >
> > > > Hi,
> > > >
> > > > [sending as plain text to l-o]
> > > >
> > > > Could you please comment on this patch.
> > > >
> > > > From: Sripal Bagadia
> > > > Date: Tue
RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
Sripal,
> Currently, display driver maps the video buffers to userspace with
> VM_RESERVED flag and pgprot_writecombine(). We are considering changing
> pgprot_writecombine() to pgprot_noncached() to eliminate the need of all
> cache maintenance overheads for video buffers.
>
-- Is this change in the current LO kernel ?
I agree there is an overhead of flushing the cache by calling get_user_pages
function. But there is some additional stuff that this function does and I am
afraid that by-passing this function call for a Buffer that has VM_RESERVED
flag and the BUFFERABLBE flags might create issues.
The only reason get_user_pages is not used for the buffer that has VM_IO flag
set is get_user_pages fails if this flag is set for the buffer. I am not sure
if it is safe to by-pass the get_user_pages function call for buffer that has
VM_RESERVED flag set though.
Thank you,
Best regards,
Hari
> -Original Message-
> From: Bagadia, Sripal
> Sent: Thursday, June 11, 2009 11:24 AM
> To: Hiroshi DOYU; Ramirez Luna, Omar
> Cc: felipe.contre...@gmail.com; ameya.pala...@nokia.com; Menon, Nishanth;
> Kanigeri, Hari; linux-omap@vger.kernel.org
> Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
>
> > Would it be possible to tell the case/path, where
> L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
>
> Currently, display driver maps the video buffers to userspace with
> VM_RESERVED flag and pgprot_writecombine(). We are considering changing
> pgprot_writecombine() to pgprot_noncached() to eliminate the need of all
> cache maintenance overheads for video buffers.
>
> Regarding Felipe's comment:
> > L_PTE_BUFFERABLE is obsolete, isn't it? L_PTE_MT_BUFFERABLE should be
> used instead.
>
> I was working on 2.6.27.10, and agree that this needs to be updated for
> newer kernels.
>
>
> Regards,
> Sripal
>
> -Original Message-
> From: Hiroshi DOYU [mailto:hiroshi.d...@nokia.com]
> Sent: Thursday, June 11, 2009 2:16 AM
> To: Ramirez Luna, Omar
> Cc: felipe.contre...@gmail.com; ameya.pala...@nokia.com; Menon, Nishanth;
> Bagadia, Sripal; Kanigeri, Hari; linux-omap@vger.kernel.org
> Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
>
> From: Hiroshi DOYU
> Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> Date: Wed, 10 Jun 2009 10:25:39 +0300 (EEST)
>
> > From: "ext Ramirez Luna, Omar"
> > Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> > Date: Wed, 10 Jun 2009 01:18:29 +0200
> >
> > > Hi,
> > >
> > > [sending as plain text to l-o]
> > >
> > > Could you please comment on this patch.
> > >
> > > From: Sripal Bagadia
> > > Date: Tue, 9 Jun 2009 16:05:09 -0500
> > > Subject: [PATCH] DSPBRIDGE: Video Playback Cache Optimization
> > >
> > > Avoid get_user_pages cache flush overheads for uncached & reserved
> > > buffers (e.g. display & camera buffers).
> >
> > Would it be possible to tell the case/path, where no
> > L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
>
> To be correct,
> "where L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED"
>
> > >
> > > Signed-off-by: Sripal Bagadia
> > > ---
> > > drivers/dsp/bridge/wmd/tiomap3430.c | 4 +++-
> > > 1 files changed, 3 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/drivers/dsp/bridge/wmd/tiomap3430.c
> > > b/drivers/dsp/bridge/wmd/tiomap3430.c
> > > index 7a9603d..a2f32e8 100644
> > > --- a/drivers/dsp/bridge/wmd/tiomap3430.c
> > > +++ b/drivers/dsp/bridge/wmd/tiomap3430.c
> > > @@ -1461,7 +1461,9 @@ static DSP_STATUS WMD_BRD_MemMap(struct
> > > WMD_DEV_CONTEXT *hDevContext,
> > > goto func_cont;
> > > }
> > >
> > > - if (vma->vm_flags & VM_IO) {
> > > + if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED)
> > > +&&
> > > + (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE)
> > > +&&
> > > + (~pgprot_val(vma->vm_page_prot) &
> > > +L_PTE_BUFFERABLE))) {
> > > numUsrPgs = ulNumBytes / PG_SIZE_4K;
> > > mpuAddr = ulMpuAddr;
> > > DBG_Trace(DBG_LEVEL4,
> "WMD_BRD_MemMap:numOfActualTabEntries=%d,"
> > > --
> > > 1.6.2.4
> > >
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RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> Would it be possible to tell the case/path, where
> L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
Currently, display driver maps the video buffers to userspace with VM_RESERVED
flag and pgprot_writecombine(). We are considering changing
pgprot_writecombine() to pgprot_noncached() to eliminate the need of all cache
maintenance overheads for video buffers.
Regarding Felipe's comment:
> L_PTE_BUFFERABLE is obsolete, isn't it? L_PTE_MT_BUFFERABLE should be used
> instead.
I was working on 2.6.27.10, and agree that this needs to be updated for newer
kernels.
Regards,
Sripal
-Original Message-
From: Hiroshi DOYU [mailto:hiroshi.d...@nokia.com]
Sent: Thursday, June 11, 2009 2:16 AM
To: Ramirez Luna, Omar
Cc: felipe.contre...@gmail.com; ameya.pala...@nokia.com; Menon, Nishanth;
Bagadia, Sripal; Kanigeri, Hari; linux-omap@vger.kernel.org
Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
From: Hiroshi DOYU
Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
Date: Wed, 10 Jun 2009 10:25:39 +0300 (EEST)
> From: "ext Ramirez Luna, Omar"
> Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> Date: Wed, 10 Jun 2009 01:18:29 +0200
>
> > Hi,
> >
> > [sending as plain text to l-o]
> >
> > Could you please comment on this patch.
> >
> > From: Sripal Bagadia
> > Date: Tue, 9 Jun 2009 16:05:09 -0500
> > Subject: [PATCH] DSPBRIDGE: Video Playback Cache Optimization
> >
> > Avoid get_user_pages cache flush overheads for uncached & reserved
> > buffers (e.g. display & camera buffers).
>
> Would it be possible to tell the case/path, where no
> L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
To be correct,
"where L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED"
> >
> > Signed-off-by: Sripal Bagadia
> > ---
> > drivers/dsp/bridge/wmd/tiomap3430.c | 4 +++-
> > 1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/dsp/bridge/wmd/tiomap3430.c
> > b/drivers/dsp/bridge/wmd/tiomap3430.c
> > index 7a9603d..a2f32e8 100644
> > --- a/drivers/dsp/bridge/wmd/tiomap3430.c
> > +++ b/drivers/dsp/bridge/wmd/tiomap3430.c
> > @@ -1461,7 +1461,9 @@ static DSP_STATUS WMD_BRD_MemMap(struct
> > WMD_DEV_CONTEXT *hDevContext,
> > goto func_cont;
> > }
> >
> > - if (vma->vm_flags & VM_IO) {
> > + if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED)
> > +&&
> > + (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE)
> > +&&
> > + (~pgprot_val(vma->vm_page_prot) &
> > +L_PTE_BUFFERABLE))) {
> > numUsrPgs = ulNumBytes / PG_SIZE_4K;
> > mpuAddr = ulMpuAddr;
> > DBG_Trace(DBG_LEVEL4, "WMD_BRD_MemMap:numOfActualTabEntries=%d,"
> > --
> > 1.6.2.4
> >
--
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Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
From: Hiroshi DOYU
Subject: Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
Date: Wed, 10 Jun 2009 10:25:39 +0300 (EEST)
> From: "ext Ramirez Luna, Omar"
> Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
> Date: Wed, 10 Jun 2009 01:18:29 +0200
>
> > Hi,
> >
> > [sending as plain text to l-o]
> >
> > Could you please comment on this patch.
> >
> > From: Sripal Bagadia
> > Date: Tue, 9 Jun 2009 16:05:09 -0500
> > Subject: [PATCH] DSPBRIDGE: Video Playback Cache Optimization
> >
> > Avoid get_user_pages cache flush overheads for uncached & reserved
> > buffers (e.g. display & camera buffers).
>
> Would it be possible to tell the case/path,
> where no L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
To be correct,
"where L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED"
> >
> > Signed-off-by: Sripal Bagadia
> > ---
> > drivers/dsp/bridge/wmd/tiomap3430.c | 4 +++-
> > 1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/dsp/bridge/wmd/tiomap3430.c
> > b/drivers/dsp/bridge/wmd/tiomap3430.c
> > index 7a9603d..a2f32e8 100644
> > --- a/drivers/dsp/bridge/wmd/tiomap3430.c
> > +++ b/drivers/dsp/bridge/wmd/tiomap3430.c
> > @@ -1461,7 +1461,9 @@ static DSP_STATUS WMD_BRD_MemMap(struct
> > WMD_DEV_CONTEXT *hDevContext,
> > goto func_cont;
> > }
> >
> > - if (vma->vm_flags & VM_IO) {
> > + if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED) &&
> > + (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE) &&
> > + (~pgprot_val(vma->vm_page_prot) & L_PTE_BUFFERABLE))) {
> > numUsrPgs = ulNumBytes / PG_SIZE_4K;
> > mpuAddr = ulMpuAddr;
> > DBG_Trace(DBG_LEVEL4, "WMD_BRD_MemMap:numOfActualTabEntries=%d,"
> > --
> > 1.6.2.4
> >
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Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
From: "ext Ramirez Luna, Omar"
Subject: RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
Date: Wed, 10 Jun 2009 01:18:29 +0200
> Hi,
>
> [sending as plain text to l-o]
>
> Could you please comment on this patch.
>
> From: Sripal Bagadia
> Date: Tue, 9 Jun 2009 16:05:09 -0500
> Subject: [PATCH] DSPBRIDGE: Video Playback Cache Optimization
>
> Avoid get_user_pages cache flush overheads for uncached & reserved
> buffers (e.g. display & camera buffers).
Would it be possible to tell the case/path,
where no L_PTE_CACHEABLE/L_PTE_BUFFERABLE is set with VM_IO/VM_RESERVED ?
>
> Signed-off-by: Sripal Bagadia
> ---
> drivers/dsp/bridge/wmd/tiomap3430.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/dsp/bridge/wmd/tiomap3430.c
> b/drivers/dsp/bridge/wmd/tiomap3430.c
> index 7a9603d..a2f32e8 100644
> --- a/drivers/dsp/bridge/wmd/tiomap3430.c
> +++ b/drivers/dsp/bridge/wmd/tiomap3430.c
> @@ -1461,7 +1461,9 @@ static DSP_STATUS WMD_BRD_MemMap(struct WMD_DEV_CONTEXT
> *hDevContext,
> goto func_cont;
> }
>
> - if (vma->vm_flags & VM_IO) {
> + if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED) &&
> + (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE) &&
> + (~pgprot_val(vma->vm_page_prot) & L_PTE_BUFFERABLE))) {
> numUsrPgs = ulNumBytes / PG_SIZE_4K;
> mpuAddr = ulMpuAddr;
> DBG_Trace(DBG_LEVEL4, "WMD_BRD_MemMap:numOfActualTabEntries=%d,"
> --
> 1.6.2.4
>
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RE: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
Hi,
[sending as plain text to l-o]
Could you please comment on this patch.
From: Sripal Bagadia
Date: Tue, 9 Jun 2009 16:05:09 -0500
Subject: [PATCH] DSPBRIDGE: Video Playback Cache Optimization
Avoid get_user_pages cache flush overheads for uncached & reserved
buffers (e.g. display & camera buffers).
Signed-off-by: Sripal Bagadia
---
drivers/dsp/bridge/wmd/tiomap3430.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/dsp/bridge/wmd/tiomap3430.c
b/drivers/dsp/bridge/wmd/tiomap3430.c
index 7a9603d..a2f32e8 100644
--- a/drivers/dsp/bridge/wmd/tiomap3430.c
+++ b/drivers/dsp/bridge/wmd/tiomap3430.c
@@ -1461,7 +1461,9 @@ static DSP_STATUS WMD_BRD_MemMap(struct WMD_DEV_CONTEXT
*hDevContext,
goto func_cont;
}
- if (vma->vm_flags & VM_IO) {
+ if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED) &&
+ (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE) &&
+ (~pgprot_val(vma->vm_page_prot) & L_PTE_BUFFERABLE))) {
numUsrPgs = ulNumBytes / PG_SIZE_4K;
mpuAddr = ulMpuAddr;
DBG_Trace(DBG_LEVEL4, "WMD_BRD_MemMap:numOfActualTabEntries=%d,"
--
1.6.2.4
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Re: [RFC][PATCH] DSPBRIDGE: Video Playback Cache Optimization
On Wed, Jun 10, 2009 at 12:39 AM, Ramirez Luna, Omar wrote:
> Hi,
>
>
>
> Could you please comment on this patch.
>
>
>
> From: Sripal Bagadia
>
> Date: Tue, 9 Jun 2009 16:05:09 -0500
>
> Subject: [PATCH] DSPBRIDGE: Video Playback Cache Optimization
>
>
>
> Avoid get_user_pages cache flush overheads for uncached & reserved
>
> buffers (e.g. display & camera buffers).
>
>
>
> Signed-off-by: Sripal Bagadia
>
> ---
>
> drivers/dsp/bridge/wmd/tiomap3430.c | 4 +++-
>
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
>
>
> diff --git a/drivers/dsp/bridge/wmd/tiomap3430.c
> b/drivers/dsp/bridge/wmd/tiomap3430.c
>
> index 7a9603d..a2f32e8 100644
>
> --- a/drivers/dsp/bridge/wmd/tiomap3430.c
>
> +++ b/drivers/dsp/bridge/wmd/tiomap3430.c
>
> @@ -1461,7 +1461,9 @@ static DSP_STATUS WMD_BRD_MemMap(struct
> WMD_DEV_CONTEXT *hDevContext,
>
> goto func_cont;
>
> }
>
>
>
> - if (vma->vm_flags & VM_IO) {
>
> + if ((vma->vm_flags & VM_IO) | ((vma->vm_flags & VM_RESERVED) &&
>
> + (~pgprot_val(vma->vm_page_prot) & L_PTE_CACHEABLE) &&
>
> + (~pgprot_val(vma->vm_page_prot) & L_PTE_BUFFERABLE))) {
L_PTE_BUFFERABLE is obsolete, isn't it? L_PTE_MT_BUFFERABLE should be
used instead.
--
Felipe Contreras
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