thank you for your comments.
your second comment has no any problem as I said before, user virtual
addess could be translated in page unit. but the problem, as you said,
is that when cpu access to the memory in user mode, the memory
allocated by malloc, page fault occurs so we can't find pfn to user
virtual address. I missed that. but I think we could resolve this one.
as before, user application allocates memory through malloc function
and then send it to device driver(using userptr feature). if the pfn
is null when device driver translated user virtual address in page
unit then it allocates phsical memory in page unit using some
interface such as alloc_page() and then mapping them. when pfn is
null, to check it and allocate physical memory in page unit could be
processed by videobuf2.
of course, videobuf2 has no any duty considered for system mmu. so
videobuf2 just provides callback for 3rd party and any platform with
system mmu such as Samsung SoC C210 implements the function(allocating
physical memory and mapping it) and registers it to callback of
videobuf2. by doing so, I think your first comment could be cleared.
please, feel free to give me your opinion and pointing out.
thank you.
2011년 1월 7일 오전 8:57, Jonghun Han [off-list ref]님의 말:
Hello,
There are two reasons why malloc isn't suitable for it.
The first is that malloc doesn't allocate memory when malloc is called.
So driver or vb2 cannot find PFN for it in the VIDIOC_QBUF.
The second is that malloc uses 4KB page allocation.
SYS.MMU(IO-MMU) can handle scattered memory. But it has a penalty when TLB
miss is occurred.
So as possible as physically contiguous pages are needed for performance
enhancement.
So new allocator which can clear two main issues is needed.
Best regards,
quoted
-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-
owner@vger.kernel.org] On Behalf Of InKi Dae
Sent: Thursday, January 06, 2011 10:25 PM
To: linux-media@vger.kernel.org
Subject: Memory sharing issue by application on V4L2 based device driver
with
quoted
system mmu.
Hello, all.
I'd like to discuss memory sharing issue by application on v4l2 based
device driver
quoted
with system mmu and get some advices about that.
Now I am working on Samsung SoC C210 platform and this platform has some
multimedia devices with system mmu such as fimc, and mfc also we have
implemented device drivers for them. those drivers are based on V4L2
framework
quoted
with videobuf2. for system mmu of each device, we used VCM(Virtual
Contiguous
quoted
Memory) framework.
Simply, VCM framework provides physical memory, device virtual memory
allocation and memory mapping between them. when device driver is
initialized or
quoted
operated by user application, each driver allocates physical memory and
device
quoted
virtual memory and then mapping using VCM interface.
refer to below link for more detail.
http://www.spinics.net/lists/linux-media/msg26548.html
Physical memory access process is as the following.
DVA PA
device --------------> system mmu ------------------> physical memory
DVA : device virtual address.
PA : physical address.
like this, device virtual address should be set to buffer(source or
destination) register of multimedia device.
the problem is that application want to share own memory with any device
driver to
quoted
avoid memory copy. in other words, user-allocated memory could be source
or
quoted
destination memory of multimedia device driver.
let's see the diagram below.
user application
|
|
|
|
| 1. UVA(allocated by malloc)
|
|
＼|/ 2. UVA(in page unit)
-----> multimedia device driver -------------------> videobuf2
|
| | ^ |
| | | |
| | -------------------------------------------
| | 3. PA(in page unit)
| |
| | 4. PA(in page unit)
6. DVA | |
| |
| |
| ＼|/
|
| Virtual Contiguous Memory ---------
| |
| | ^ |
| | | | 5. map PA to DVA
| | | |
| | | |
------------- -------------------------
PA : physical address.
UVA : user virtual address.
DVA : device virtual address.
1. user application allocates user space memory through malloc function
and
quoted
sending it to multimedia device driver based on v4l2 framework through
userptr
quoted
feature.
2, 3. multimedia device driver gets translated physical address from
videobuf2 framework in page unit.
4, 5. multimedia device driver gets allocated device virtual address and
mapping it
quoted
to physical address and then mapping them through VCM interface.
6. multimedia device driver sets device virtual address from VCM to
buffer register.
quoted
the diagram above is fully theoretical so I wonder that this way is
reasonable and
quoted
has some problems also what should be considered.
thank you for your interesting.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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To unsubscribe from this list: send the line "unsubscribe linux-media" in
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quoted
of a message to majordomo@vger.kernel.org More majordomo info at
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Hello,
That's not a translation issue. What I mention is the size of allocation.
The malloc uses 4KB page allocation and SYS.MMU can handle it.
But 64KB or 1MB physically contiguous memory is better than 4KB page in the
point of performance.
Best regards,
-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-
owner@vger.kernel.org] On Behalf Of InKi Dae
Sent: Friday, January 07, 2011 11:17 AM
To: Jonghun Han
Cc: linux-media@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
linux-fbdev;
kyungmin.park@samsung.com
Subject: Re: Memory sharing issue by application on V4L2 based device
driver
with system mmu.
thank you for your comments.
your second comment has no any problem as I said before, user virtual
addess
could be translated in page unit. but the problem, as you said, is that
when cpu
access to the memory in user mode, the memory allocated by malloc, page
fault
occurs so we can't find pfn to user virtual address. I missed that. but I
think we
could resolve this one.
as before, user application allocates memory through malloc function and
then
send it to device driver(using userptr feature). if the pfn is null when
device driver
translated user virtual address in page unit then it allocates phsical
memory in
page unit using some interface such as alloc_page() and then mapping
them. when
pfn is null, to check it and allocate physical memory in page unit could
be
processed by videobuf2.
of course, videobuf2 has no any duty considered for system mmu. so
videobuf2 just provides callback for 3rd party and any platform with
system mmu
such as Samsung SoC C210 implements the function(allocating physical
memory
and mapping it) and registers it to callback of videobuf2. by doing so, I
think your
first comment could be cleared.
please, feel free to give me your opinion and pointing out.
thank you.
2011년 1월 7일 오전 8:57, Jonghun Han [off-list ref]님의 말:
quoted
Hello,
There are two reasons why malloc isn't suitable for it.
The first is that malloc doesn't allocate memory when malloc is called.
So driver or vb2 cannot find PFN for it in the VIDIOC_QBUF.
The second is that malloc uses 4KB page allocation.
SYS.MMU(IO-MMU) can handle scattered memory. But it has a penalty when
TLB miss is occurred.
So as possible as physically contiguous pages are needed for
performance enhancement.
So new allocator which can clear two main issues is needed.
Best regards,
quoted
-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-
owner@vger.kernel.org] On Behalf Of InKi Dae
Sent: Thursday, January 06, 2011 10:25 PM
To: linux-media@vger.kernel.org
Subject: Memory sharing issue by application on V4L2 based device
driver
with
quoted
system mmu.
Hello, all.
I'd like to discuss memory sharing issue by application on v4l2 based
device driver
quoted
with system mmu and get some advices about that.
Now I am working on Samsung SoC C210 platform and this platform has
some multimedia devices with system mmu such as fimc, and mfc also we
have implemented device drivers for them. those drivers are based on
V4L2
framework
quoted
with videobuf2. for system mmu of each device, we used VCM(Virtual
Contiguous
quoted
Memory) framework.
Simply, VCM framework provides physical memory, device virtual
memory allocation and memory mapping between them. when device driver
is
initialized or
quoted
operated by user application, each driver allocates physical memory
and
device
quoted
virtual memory and then mapping using VCM interface.
refer to below link for more detail.
http://www.spinics.net/lists/linux-media/msg26548.html
Physical memory access process is as the following.
DVA PA
device --------------> system mmu ------------------> physical memory
DVA : device virtual address.
PA : physical address.
like this, device virtual address should be set to buffer(source or
destination) register of multimedia device.
the problem is that application want to share own memory with any
device
driver to
quoted
avoid memory copy. in other words, user-allocated memory could be
source
or
quoted
destination memory of multimedia device driver.
let's see the diagram below.
user application
|
|
|
|
| 1. UVA(allocated by malloc)
|
|
＼|/ 2. UVA(in page unit)
-----> multimedia device driver -------------------> videobuf2
|
| | ^ |
| | | |
| | -------------------------------------------
| | 3. PA(in page unit)
| |
| | 4. PA(in page unit)
6. DVA | |
| |
| |
| ＼|/
|
| Virtual Contiguous Memory ---------
| |
| | ^ |
| | | | 5. map PA to DVA
| | | |
| | | |
------------- -------------------------
PA : physical address.
UVA : user virtual address.
DVA : device virtual address.
1. user application allocates user space memory through malloc
function
and
quoted
sending it to multimedia device driver based on v4l2 framework
through
userptr
quoted
feature.
2, 3. multimedia device driver gets translated physical address from
videobuf2 framework in page unit.
4, 5. multimedia device driver gets allocated device virtual address
and
mapping it
quoted
to physical address and then mapping them through VCM interface.
6. multimedia device driver sets device virtual address from VCM to
buffer register.
quoted
the diagram above is fully theoretical so I wonder that this way is
reasonable and
quoted
has some problems also what should be considered.
thank you for your interesting.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
To unsubscribe from this list: send the line "unsubscribe
linux-media" in
the body
quoted
of a message to majordomo@vger.kernel.org More majordomo info at
http://vger.kernel.org/majordomo-info.html
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Hello, Mr. Jonghun.
please, note that user process's pgd and device's pgd with system mmu
are differnent. first, the memory allocated by user malloc should be
mapped to physical memory in page unit because user app also should be
accessed to own memory region. and when mapping the physical memory to
device virtual address, it creates page table entry for 64k or 1M and
then could map physical address to those entries. therefore what you
mention has no problem.
actual issue is not to need demend paging, some issues we don't
understand may exist as side effects.
thank you.
Jonghun Han 쓴 글:
Hello,
That's not a translation issue. What I mention is the size of allocation.
The malloc uses 4KB page allocation and SYS.MMU can handle it.
But 64KB or 1MB physically contiguous memory is better than 4KB page in the
point of performance.
Best regards,
quoted
-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-
owner@vger.kernel.org] On Behalf Of InKi Dae
Sent: Friday, January 07, 2011 11:17 AM
To: Jonghun Han
Cc: linux-media@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
linux-fbdev;
quoted
kyungmin.park@samsung.com
Subject: Re: Memory sharing issue by application on V4L2 based device
driver
quoted
with system mmu.
thank you for your comments.
your second comment has no any problem as I said before, user virtual
addess
quoted
could be translated in page unit. but the problem, as you said, is that
when cpu
quoted
access to the memory in user mode, the memory allocated by malloc, page
fault
quoted
occurs so we can't find pfn to user virtual address. I missed that. but I
think we
quoted
could resolve this one.
as before, user application allocates memory through malloc function and
then
quoted
send it to device driver(using userptr feature). if the pfn is null when
device driver
quoted
translated user virtual address in page unit then it allocates phsical
memory in
quoted
page unit using some interface such as alloc_page() and then mapping
them. when
quoted
pfn is null, to check it and allocate physical memory in page unit could
be
quoted
processed by videobuf2.
of course, videobuf2 has no any duty considered for system mmu. so
videobuf2 just provides callback for 3rd party and any platform with
system mmu
quoted
such as Samsung SoC C210 implements the function(allocating physical
memory
quoted
and mapping it) and registers it to callback of videobuf2. by doing so, I
think your
quoted
first comment could be cleared.
please, feel free to give me your opinion and pointing out.
thank you.
2011년 1월 7일 오전 8:57, Jonghun Han [off-list ref]님의 말:
quoted
Hello,
There are two reasons why malloc isn't suitable for it.
The first is that malloc doesn't allocate memory when malloc is called.
So driver or vb2 cannot find PFN for it in the VIDIOC_QBUF.
The second is that malloc uses 4KB page allocation.
SYS.MMU(IO-MMU) can handle scattered memory. But it has a penalty when
TLB miss is occurred.
So as possible as physically contiguous pages are needed for
performance enhancement.
So new allocator which can clear two main issues is needed.
Best regards,
quoted
-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-
owner@vger.kernel.org] On Behalf Of InKi Dae
Sent: Thursday, January 06, 2011 10:25 PM
To: linux-media@vger.kernel.org
Subject: Memory sharing issue by application on V4L2 based device
driver
with
quoted
system mmu.
Hello, all.
I'd like to discuss memory sharing issue by application on v4l2 based
device driver
quoted
with system mmu and get some advices about that.
Now I am working on Samsung SoC C210 platform and this platform has
some multimedia devices with system mmu such as fimc, and mfc also we
have implemented device drivers for them. those drivers are based on
V4L2
framework
quoted
with videobuf2. for system mmu of each device, we used VCM(Virtual
Contiguous
quoted
Memory) framework.
Simply, VCM framework provides physical memory, device virtual
memory allocation and memory mapping between them. when device driver
is
initialized or
quoted
operated by user application, each driver allocates physical memory
and
device
quoted
virtual memory and then mapping using VCM interface.
refer to below link for more detail.
http://www.spinics.net/lists/linux-media/msg26548.html
Physical memory access process is as the following.
DVA PA
device --------------> system mmu ------------------> physical memory
DVA : device virtual address.
PA : physical address.
like this, device virtual address should be set to buffer(source or
destination) register of multimedia device.
the problem is that application want to share own memory with any
device
driver to
quoted
avoid memory copy. in other words, user-allocated memory could be
source
or
quoted
destination memory of multimedia device driver.
let's see the diagram below.
user application
|
|
|
|
| 1. UVA(allocated by malloc)
|
|
＼|/ 2. UVA(in page unit)
-----> multimedia device driver -------------------> videobuf2
|
| | ^ |
| | | |
| | -------------------------------------------
| | 3. PA(in page unit)
| |
| | 4. PA(in page unit)
6. DVA | |
| |
| |
| ＼|/
|
| Virtual Contiguous Memory ---------
| |
| | ^ |
| | | | 5. map PA to DVA
| | | |
| | | |
------------- -------------------------
PA : physical address.
UVA : user virtual address.
DVA : device virtual address.
1. user application allocates user space memory through malloc
function
and
quoted
sending it to multimedia device driver based on v4l2 framework
through
userptr
quoted
feature.
2, 3. multimedia device driver gets translated physical address from
videobuf2 framework in page unit.
4, 5. multimedia device driver gets allocated device virtual address
and
mapping it
quoted
to physical address and then mapping them through VCM interface.
6. multimedia device driver sets device virtual address from VCM to
buffer register.
quoted
the diagram above is fully theoretical so I wonder that this way is
reasonable and
quoted
has some problems also what should be considered.
thank you for your interesting.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
To unsubscribe from this list: send the line "unsubscribe
linux-media" in
the body
quoted
of a message to majordomo@vger.kernel.org More majordomo info at
http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
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quoted
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More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fre, 2011-01-07 at 11:17 +0900, InKi Dae wrote:
thank you for your comments.
your second comment has no any problem as I said before, user virtual
addess could be translated in page unit. but the problem, as you said,
is that when cpu access to the memory in user mode, the memory
allocated by malloc, page fault occurs so we can't find pfn to user
virtual address. I missed that. but I think we could resolve this one.
as before, user application allocates memory through malloc function
and then send it to device driver(using userptr feature). if the pfn
is null when device driver translated user virtual address in page
unit then it allocates phsical memory in page unit using some
interface such as alloc_page() and then mapping them. when pfn is
null, to check it and allocate physical memory in page unit could be
processed by videobuf2.
of course, videobuf2 has no any duty considered for system mmu. so
videobuf2 just provides callback for 3rd party and any platform with
system mmu such as Samsung SoC C210 implements the function(allocating
physical memory and mapping it) and registers it to callback of
videobuf2. by doing so, I think your first comment could be cleared.
FWIW, TTM (drivers/gpu/drm/ttm, include/drm/ttm) is designed and used
for managing memory between CPU/GPU and kernel/userspace access. I
haven't looked at your requirements in detail, but if you haven't looked
at TTM yet, it sounds like it might be worth a look.
--
Earthling Michel Dänzer | http://www.vmware.com
Libre software enthusiast | Debian, X and DRI developer
Michel Dänzer 쓴 글:
On Fre, 2011-01-07 at 11:17 +0900, InKi Dae wrote:
quoted
thank you for your comments.
your second comment has no any problem as I said before, user virtual
addess could be translated in page unit. but the problem, as you said,
is that when cpu access to the memory in user mode, the memory
allocated by malloc, page fault occurs so we can't find pfn to user
virtual address. I missed that. but I think we could resolve this one.
as before, user application allocates memory through malloc function
and then send it to device driver(using userptr feature). if the pfn
is null when device driver translated user virtual address in page
unit then it allocates phsical memory in page unit using some
interface such as alloc_page() and then mapping them. when pfn is
null, to check it and allocate physical memory in page unit could be
processed by videobuf2.
of course, videobuf2 has no any duty considered for system mmu. so
videobuf2 just provides callback for 3rd party and any platform with
system mmu such as Samsung SoC C210 implements the function(allocating
physical memory and mapping it) and registers it to callback of
videobuf2. by doing so, I think your first comment could be cleared.
FWIW, TTM (drivers/gpu/drm/ttm, include/drm/ttm) is designed and used
for managing memory between CPU/GPU and kernel/userspace access. I
haven't looked at your requirements in detail, but if you haven't looked
at TTM yet, it sounds like it might be worth a look.
Thank you for your advice. I would look at TTM driver.
Sorry for late reply.
Samsung SoC C210 has many multimedia IPs.
Each IP has its own MMU named SYSTEM MMU like CPU's MMU.
So it can handle discontiguous memory using device own virtual address.
What Inki Dae wants to discuss is how to allocate the memory and how to
share it with other multimedia IPs.
Thank you for interesting.
Best regards,
-----Original Message-----
From: linux-fbdev-owner@vger.kernel.org [mailto:linux-fbdev-
owner@vger.kernel.org] On Behalf Of Konrad Rzeszutek Wilk
Sent: Wednesday, January 12, 2011 2:35 AM
To: Jonghun Han
Cc: 'InKi Dae'; linux-media@vger.kernel.org;
linux-arm-kernel@lists.infradead.org;
'linux-fbdev'; kyungmin.park@samsung.com
Subject: Re: Memory sharing issue by application on V4L2 based device
driver
with system mmu.
.. snip..
quoted
But 64KB or 1MB physically contiguous memory is better than 4KB page
in the point of performance.
Could you explain that in more details please? I presume you are talking
about a
CPU that has a MMU unit, right?
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