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 constant from libdc that can give you the answer, or you have to get it from the /proc/meminfo? Now, if you can only get it from the /proc/meminfo, is this info always there? As far as I remember, you can compile kernels without the /proc/meminfo... And yes, probably we would have to get rid of this issue and look for an alternative way. Still, from a technical point of view, I am really curious if this information on the size of VmallocChunk is available to the developer 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=<size> to > | increase size.>> kernel error message thing). The plan how to resolve the > | 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 like > | VMALLOC_RESERVED or something around this area (a function like > | getpagesize or sysconf)? It will do a great deal to solve the problematic > | 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. Ignoring. > | > > [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. Ignoring. > | > > [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=<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 stop > | > > listening on channel 1 > | > > [17723535.676000] video1394_1: On release: Iso receive context 0 stop > | > > 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: > | > VIDEO1394_IOC_LISTEN_CHANNEL ioctl 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 problem with the limit in the > | > size of the allocated DMA buffer is 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. > | > > | > but at boot time you can specify how much virtually contiguous memory > | > you want with the parameter vmalloc, so if you want about 512Mbytes of > | > memory for vmalloc you should add the parameter vmalloc=536870912 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 /boot/vmlinuz-2.6.15-27-686 root=/dev/sda2 > | > vmalloc=536870912 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 > | > | [...] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
