3 Feb
2017
3 Feb
'17
6:04 p.m.
I'm using the latest fosphor from git
(7b6b9961bc2d9b84daeb42a5c8f8aeba293d207c) and am seeing two weird (and I
believe related) issues. Firstly, I see the following error:
[+] Selected device: TITAN X (Pascal)
[!] CL Error (-30, /home/user/gr-fosphor/lib/fosphor/cl.c:409): Unable to
queue clear of spectrum buffer
This is CL_INVALID_VALUE returning from clEnqueueFillBuffer, so I added
some debug fprints to cl.c to see what parameters were being passed
into clEnqueueFillBuffer:
Edits:
fprintf(stderr, "size = %d\n", 2 * 2 * sizeof(cl_float) * FOSPHOR_FFT_LEN);
fprintf(stderr, "pattern_size = %d\n", sizeof(float));
fprintf(stderr, "pattern = %p\n", &noise_floor);
fprintf(stderr, "offset = %d\n", 0);
Output:
size = 16384
pattern_size = 4
pattern = 0x7fb66b7fdd2c
offset = 0
These parameters look like they shouldn't cause CL_INVALID_VALUE:
https://www.khronos.org/registry/OpenCL/sdk/2.0/docs/man/xhtml/clEnqueueFil…
But there is this one condition that might be met, which is that somehow
size (16384) is larger than the underlying buffer (cl->mem_spectrum). The
underlying OpenGL buffer being too small brings me to my next (I believe
related) issue. The spectrum plot in fosphor is weirdly pixelated, please
see the attachment, which shows a screencap from "osmocom_fft -F -f 100e6
-g 20 -s 10e6".
Where is the cl->mem_spectrum buffer ultimately declared / initialized? My
OpenCL / OpenGL sharing knowledge is nonexistent, any pointers for how I
can help debug this issue?
Output of clinfo is attached as well, and I'm on Ubuntu 16.04 on x86_64.
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622
3 Feb
3 Feb
8:06 p.m.
Hi Raj,
I'm using the latest fosphor from git
(7b6b9961bc2d9b84daeb42a5c8f8aeba293d207c) and am seeing two weird (and I
believe related) issues. Firstly, I see the following error:
[+] Selected device: TITAN X (Pascal)
[!] CL Error (-30, /home/user/gr-fosphor/lib/fosphor/cl.c:409): Unable to
queue clear of spectrum buffer
That's really weird indeed. Although I've seen it before. Can't
remember exactly what it was though ...
This is CL_INVALID_VALUE returning from
clEnqueueFillBuffer, so I added some
debug fprints to cl.c to see what parameters were being passed into
clEnqueueFillBuffer:
Watchout that CL 1.2 might not be supported by NVidia's driver and so
it might use the fallback path defined in cl_compat.c
But there is this one condition that might be met,
which is that somehow
size (16384) is larger than the underlying buffer (cl->mem_spectrum). The
underlying OpenGL buffer being too small brings me to my next (I believe
related) issue. The spectrum plot in fosphor is weirdly pixelated, please
see the attachment, which shows a screencap from "osmocom_fft -F -f 100e6 -g
20 -s 10e6".
Where is the cl->mem_spectrum buffer ultimately declared / initialized? My
OpenCL / OpenGL sharing knowledge is nonexistent, any pointers for how I can
help debug this issue?
So, there is two way that mem_spectrum can be initialized depending on
wether CL/GL sharing is active or not.
Look into cl_init_buffers_gl and cl_init_buffers_nogl basically.
But I've seen drivers do things that are not spec compliant
unfortunately ... and other than trying random stuff to see exactly
what they don't like, I'm not sure what to do.
Cheers,
Sylvain
4 Feb
4 Feb
10:44 a.m.
Hi,
Actually the reason I'm not seeing it anymore on my setup is because I
don't have any machine with CL/GL sharing working any more ... I
changed laptop since and I can't get CL/GL sharing working with
optirun and recent nvidia drivers ...
One thing I would point out though is that if you have CL/GL sharing
working, you can pretty much comment the entire call to
cl_queue_clear_buffers because the GL side of things will clear the
buffers already and they are the same. The independent clearing of the
CL buffers only matter if they're different.
Cheers,
Sylvain
I'm using
the latest fosphor from git
(7b6b9961bc2d9b84daeb42a5c8f8aeba293d207c) and am seeing two weird (and I
believe related) issues. Firstly, I see the following error:
[+] Selected device: TITAN X (Pascal)
[!] CL Error (-30, /home/user/gr-fosphor/lib/fosphor/cl.c:409): Unable to
queue clear of spectrum buffer
That's really weird indeed. Although I've seen it before. Can't
remember exactly what it was though ...
5 Feb
5 Feb
8:36 p.m.
On Sat, Feb 4, 2017 at 4:44 AM, Sylvain Munaut <246tnt(a)gmail.com> wrote:
Hi,
Actually the reason I'm not seeing it anymore on my setup is because I
don't have any machine with CL/GL sharing working any more ... I
changed laptop since and I can't get CL/GL sharing working with
optirun and recent nvidia drivers ...
One thing I would point out though is that if you have CL/GL sharing
working, you can pretty much comment the entire call to
cl_queue_clear_buffers because the GL side of things will clear the
buffers already and they are the same. The independent clearing of the
CL buffers only matter if they're different.
I'll comment out that call for my purposes and let you know how that goes.
My guess is that resolves the -30 error but not the blocky/pixelated
spectrum histogram.
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622
> I'm using the latest fosphor from git
> (7b6b9961bc2d9b84daeb42a5c8f8aeba293d207c) and am seeing two weird
(and I
> believe related) issues. Firstly, I see the
following error:
>
> [+] Selected device: TITAN X (Pascal)
> [!] CL Error (-30, /home/user/gr-fosphor/lib/fosphor/cl.c:409): Unable
to
queue
clear of spectrum buffer
That's really weird indeed. Although I've seen it before. Can't
remember exactly what it was though ...
6 Feb
6 Feb
10:38 p.m.
Based on your comment about how your setup doesn't support GL/CL sharing, I
tried defining FLG_FOSPHOR_USE_CLGL_SHARING as 0 in private.h. Not sharing
GL objects fixes the pixelated spectrum issue! No more
cl_clear_queue_clear_buffers errors either, because the code never goes
down that path anymore.
It seems to me there is a bug in the way the histogram buffer or texture is
allocated when it is allocated through the GL code path. I'm not sure if
this is quirk of my setup/GPU/driver, or if this is a general bug; I do
have an older NVIDIA GPU and another machine on which I can try to
reproduce what I'm seeing.
Final question, what are the main downsides to NOT using CL/GL sharing? Is
there some extra copy/performance overhead?
On Sun, Feb 5, 2017 at 2:36 PM, Raj Bhattacharjea <raj.b(a)gatech.edu> wrote:
On Sat, Feb 4, 2017 at 4:44 AM, Sylvain Munaut
<246tnt(a)gmail.com> wrote:
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622
Hi,
Actually the reason I'm not seeing it anymore on my setup is because I
don't have any machine with CL/GL sharing working any more ... I
changed laptop since and I can't get CL/GL sharing working with
optirun and recent nvidia drivers ...
One thing I would point out though is that if you have CL/GL sharing
working, you can pretty much comment the entire call to
cl_queue_clear_buffers because the GL side of things will clear the
buffers already and they are the same. The independent clearing of the
CL buffers only matter if they're different.
I'll comment out that call for my purposes and let you know how that goes.
My guess is that resolves the -30 error but not the blocky/pixelated
spectrum histogram.
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622 <(404)%20407-6622>
> I'm using the latest fosphor from git
> (7b6b9961bc2d9b84daeb42a5c8f8aeba293d207c) and am seeing two weird
(and I
> believe related) issues. Firstly, I see the
following error:
>
> [+] Selected device: TITAN X (Pascal)
> [!] CL Error (-30, /home/user/gr-fosphor/lib/fosphor/cl.c:409):
Unable to
queue
clear of spectrum buffer
That's really weird indeed. Although I've seen it before. Can't
remember exactly what it was though ...
7 Feb
7 Feb
10:01 a.m.
Hi,
Based on your comment about how your setup doesn't
support GL/CL sharing, I
tried defining FLG_FOSPHOR_USE_CLGL_SHARING as 0 in private.h. Not sharing
GL objects fixes the pixelated spectrum issue! No more
cl_clear_queue_clear_buffers errors either, because the code never goes down
that path anymore.
Ok, good to know.
I need to come up with a good way to pass "options" to fosphor to be
able to configure theses things at runtime.
It seems to me there is a bug in the way the histogram
buffer or texture is
allocated when it is allocated through the GL code path. I'm not sure if
this is quirk of my setup/GPU/driver, or if this is a general bug; I do have
an older NVIDIA GPU and another machine on which I can try to reproduce what
I'm seeing.
I can't get CL/GL sharing to work at all on my optimus laptop so
unfortunately I can't even test that code path anymore.
I really need to build myself a desktop machine ....
Final question, what are the main downsides to NOT
using CL/GL sharing? Is
there some extra copy/performance overhead?
Yes. Basically the result of the CL computation is downloaded to CPU
memory, then re-uploaded as a texture.
Not only does that impose extra data copy but also more
synchronization points between CPU and GPU.
Cheers,
Sylvain
9:52 p.m.
Sylvain,
Ok, good to know.
I need to come up with a good way to pass "options" to fosphor to be
able to configure theses things at runtime.
That would be useful! Given how much I use your tool for real work, I'm
willing to contribute; do you look at pull requests on the github mirror?
Here are some other things I have often considered plumbing through as
options:
1. FFT length. It looks like you have a length 512 FFT kernel in fft.cl
already, but I think its unused. A few other FFT sizes might be useful too
for adjusting resolution bandwidth. With what you have, several other
powers of two should be implementable simply.
2. Waterfall time length. Requires some GL tricks to change the texture
size, or internally render at some fixed size and always crop and/or
downsample the texture to show the amount of time the user requested.
Thanks for the tips that resolved the issue!
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622
20 Jun
20 Jun
10:51 p.m.
I know this thread is a bit old, but it's worth mentioning that CL/GL
sharing being enabled causes fosphor to be broken altogether on my setup as
of the latest master commit (possibly earlier). Everything builds, but the
following runtime error occurs:
[!] CL Error (-5, /home/user/gr-fosphor/lib/fosphor/cl.c:480): Unable to
share spectrum VBO into OpenCL context
As previously mentioned, everything works okay if I change the value of
FLG_FOSPHOR_USE_CLGL_SHARING in private.h to 0.
Sylvain, do you always have the value of this flag as zero in your building
and testing? Or do you leave it as 1 and fosphor works because you're using
Intel CPU OpenCL or something? Maybe check in "#define
FLG_FOSPHOR_USE_CLGL_SHARING (0<<0)" into the source repo until you can
verify that this code path works correctly?
Details of my setup:
x86_64 (Xeon D)
Ubuntu 16.04
NVIDIA Titan Xp
NVIDIA Driver 375.66 from the standard Ubuntu (xenial-updates)
nvidia-opencl-icl-375 from the standard Ubuntu repos
I'm happy to test things out and will do some of my own debugging.
On Tue, Feb 7, 2017 at 3:52 PM, Raj Bhattacharjea <raj.b(a)gatech.edu> wrote:
Sylvain,
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622
Ok, good to know.
I need to come up with a good way to pass "options" to fosphor to be
able to configure theses things at runtime.
That would be useful! Given how much I use your tool for real work, I'm
willing to contribute; do you look at pull requests on the github mirror?
Here are some other things I have often considered plumbing through as
options:
1. FFT length. It looks like you have a length 512 FFT kernel in fft.cl
already, but I think its unused. A few other FFT sizes might be useful too
for adjusting resolution bandwidth. With what you have, several other
powers of two should be implementable simply.
2. Waterfall time length. Requires some GL tricks to change the texture
size, or internally render at some fixed size and always crop and/or
downsample the texture to show the amount of time the user requested.
Thanks for the tips that resolved the issue!
--
Raj Bhattacharjea, PhD
Georgia Tech Research Institute
Information and Communications Laboratory
http://www.prism.gatech.edu/~rb288/
404.407.6622 <(404)%20407-6622>
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days inactive
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days old
7 comments
2 participants
participants (2)
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Raj Bhattacharjea -
Sylvain Munaut