Re: [libdc1394-devel] =?iso-8859-1?q?allocation_failed=3A_out_of_vmal?= =?iso-8859-1?q?loc_space_error_treating_and_VIDEO1394_IOC_LISTEN_C?= =?iso-8859-1?q?HANNEL_ioctl=A0failed_problem?=

[Peter A. <the...@us...>]

On Monday 15 January 2007 05:31, Stefan Richter wrote:
> On 14 Jan, Arjan van de Ven wrote:
> > vmalloc space is limited; you really can't assume you can get any more
> > than 64Mb or so (and even then it's thight on some systems already);
>
> I suppose "grep VmallocChunk /proc/meminfo" shows what is available?

This is more the answer that I expect. But is there a way, function or=20
constant from libdc that can give you the answer, or you have to get it fro=
m=20
the /proc/meminfo? Now, if you can only get it from the /proc/meminfo, is=20
this info always there? As far as I remember, you can compile kernels witho=
ut=20
the /proc/meminfo...

And yes, probably we would have to get rid of this issue and look for an=20
alternative way. Still, from a technical point of view, I am really curious=
=20
if this information on the size of VmallocChunk is available to the develop=
er=20
in other forms...

Thank you all!

Cheers,
Peter

> > it really sounds like vmalloc space isn't the right solution for your
> > problem whatever it is (context is lost in the quoted mail)...
> > can you restate the problem to see if there's a better solution
> > possible?
>
> Thanks. Below is Peter's message to linux1394-devel. The previous
> discussion went over libdc1394-devel which I don't receive. Obviously he
> wants a really large buffer for reception of an isochronous stream. I
> guess his reason is highly application specific...
>
> | Hi all,
> |
> | I've been trying to get a resolution to the problem with vmalloc error
> | (the <<allocation failed: out of vmalloc space - use vmalloc=3D<size> to
> | increase size.>> kernel error message thing). The plan how to resolve t=
he
> | issue is simple; get the buffer size that we try to allocate
> | (vmmap.nb_buffers * vmmap.buf_size) and compare it to the
> | VMALLOC_RESERVED. If too big, error with explanation how to fix it. If
> | small, other error (usual out of mem). Problem is: how to get the
> | VMALLOC_RESERVED value for the kernel that is running? I couldn't find
> | any standard way to do that (something to apply to GNU Linux and the
> | like). All the things I could get were the default value being 128MiB :)
> | and that is it. Now, I could just put 128, but what if somebody changes
> | that, or in some new distro suddenly decides to make it different? Even
> | worse, what if it is an old kernel with 64 setting?
> |
> | Currently, in the SVN version, Damien was kind to change so that a
> | message gets printed with a full explanation of how to treat it. Still,
> | this is a compromise solution and not the elegant one that I was looking
> | for. I believe and hope that maybe somebody had this issue before and
> | could help with some suggestions...
> |
> | So, my question is: anybody knows the way to get to the kernel value li=
ke
> | VMALLOC_RESERVED or something around this area (a function like
> | getpagesize or sysconf)? It will do a great deal to solve the problemat=
ic
> | error treatment in the library...
> |
> | Thank you.
> |
> | For your reference, this is in response to this line of thinking or the
> | libdc1394-devel thread:
> | [...]
> |
> | > > When I set NUM_BUFFERS (number of DMA buffers) to a value greater
> | > > than 5 the program dies like this:
> | > >
> | > > (dc1394_capture.c) VIDEO1394_IOC_LISTEN_CHANNEL ioctl failed!
> | > > Libdc1394 error (dc1394_capture.c:dc1394_capture_setup_dma:382):
> | > > Capture is not set : Could not setup DMA capture
> |
> | [...]
> |
> | > > [17723533.496000] video1394_0: Iso receive DMA: 8 buffers of size
> | > > 6627328 allocated for a frame size 6624000, each with 1619 prgs
> | > > [17723533.516000] video1394_0: iso context 0 listen on channel 1
> | > > [17723533.712000] ieee1394: Node [1-01:1023] wants to release
> | > > broadcast channel 31. =A0Ignoring.
> | > > [17723534.448000] video1394_1: mask: 0000000000000004 usage:
> | > > 0000000000000000
> | > > [17723534.448000]
> | > > [17723534.508000] video1394_1: Iso receive DMA: 8 buffers of size
> | > > 6627328 allocated for a frame size 6624000, each with 1619 prgs
> | > > [17723534.532000] video1394_1: iso context 0 listen on channel 2
> | > > [17723534.728000] ieee1394: Node [2-01:1023] wants to release
> | > > broadcast channel 31. =A0Ignoring.
> | > > [17723535.464000] video1394_2: mask: 0000000000000008 usage:
> | > > 0000000000000000
> | > > [17723535.464000]
> | > > [17723535.464000] printk: 11 messages suppressed.
> | > > [17723535.464000] allocation failed: out of vmalloc space - use
> | > > vmalloc=3D<size> to increase size.
> | > > [17723535.464000] dma_region_alloc: vmalloc_32() failed
> | > > [17723535.464000] video1394_2: Failed to allocate dma buffer
> | > > [17723535.464000] video1394_2: Couldn't allocate ir context
> | > > [17723535.668000] video1394_0: On release: Iso receive context 0 st=
op
> | > > listening on channel 1
> | > > [17723535.676000] video1394_1: On release: Iso receive context 0 st=
op
> | > > listening on channel 2
> |
> | [...]
> |
> | > ------------------------------
> | >
> | > Message: 2
> | > Date: Fri, 05 Jan 2007 17:30:39 +0100
> | > From: Martin Peris <xxxxxxxxxxxxxxxxxxx>
> | > Subject: Re: [libdc1394-devel] [SPAM RBL] Re:
> | > =A0=A0=A0=A0=A0=A0=A0=A0VIDEO1394_IOC_LISTEN_CHANNEL=A0=A0=A0=A0ioctl=
 failed! and Bad images
> | > To: Damien Douxchamps <xxxxxxxxxxxxxxxxxxxxx>
> | > Cc: libdc1394-devel <xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
> |
> | [...]
> |
> | > I think I have some answers...
> | >
> | > I've been investigating a bit, and the =A0problem with the limit in t=
he
> | > size of the allocated DMA buffer =A0is not so obscure.
> | >
> | > vmalloc_32() allocate virtually contiguous memory (32bit addressable),
> | > the default maximum amount of memory reserved for this depends on each
> | > kernel compilation, and in my case it was set to 128Mbytes that's why=
 I
> | > had an error if tried to allocate too many buffers.
> | >
> | > =A0but at boot time you can specify how much virtually contiguous mem=
ory
> | > you want with the parameter vmalloc, so if you want about 512Mbytes of
> | > memory for vmalloc you should add the parameter vmalloc=3D536870912 to
> | > the line that defines the kernel parameters. (If you use grub there
> | > should be a line like this on /boot/grub/menu.lst)
> | >
> | > kernel =A0 =A0 =A0 =A0 =A0/boot/vmlinuz-2.6.15-27-686 root=3D/dev/sda2
> | > vmalloc=3D536870912 ro quiet splash
> | >
> | >
> | > That killed my problem with:
> | >
> | > dc1394_capture.c) VIDEO1394_IOC_LISTEN_CHANNEL ioctl failed!
> | > Libdc1394 error (dc1394_capture.c:dc1394_capture_setup_dma:382):
> | > Capture is not set : Could not setup DMA capture
> |
> | [...]