Philippe Gerum wrote:
The following patch against stock 2.2.2 improves the RTAI fifo
emulation. It reduces the overhead induced by sending highly scattered
data over a short period of time, and basically provides a much saner
implementation.
I'd be interested to have some feedback about this; I plan to change the
data streaming mode of message pipes from the native API the same way.
TIA,
I applied this patch on my linux-2.6 and 2.4 systems. The simple 'fifotestk.c'
example I posted now works fine, with no apparent memory leaks. I can now
allocate a 128 MB RTAI FIFO, which sure beats 100 KB! Thanks for the fix!
If I try to allocate a FIFO larger than the available vmalloc space, the
rtf_create routine now fails with ENOMEM, which is much better than failing on
the rtf_put call. Unfortunately, the RT-FIFO device is now EBUSY forever. I
can switch to another device, and I can allocate space for my 128 MB FIFO once
again, so that is good, at least. Here is the printk output from my program:
[ 128 MB allocation, which works ....]
Sep 11 14:43:26 kernel: fifotest_init
Sep 11 14:43:26 kernel: rtf_create returned: 2
Sep 11 14:43:26 kernel: rtf_put: 6
Sep 11 14:43:29 kernel: fifotest_cleanup
Sep 11 14:43:29 kernel: rtf_destroy returned: 0
Sep 11 14:43:32 kernel: fifotest_init
Sep 11 14:43:32 kernel: rtf_create returned: 2
Sep 11 14:43:32 kernel: rtf_put: 6
Sep 11 14:43:35 kernel: fifotest_cleanup
Sep 11 14:43:35 kernel: rtf_destroy returned: 0
[switched to 256 MB allocation here... should fail]
Sep 11 14:44:29 kernel: fifotest_init
Sep 11 14:44:29 kernel: rtf_create returned: -12
Sep 11 14:44:29 kernel: rtf_put: -22
Sep 11 14:44:33 kernel: fifotest_cleanup
Sep 11 14:44:33 kernel: rtf_destroy returned: -22
[switched back to 128 MB allocation, but the device is now busy...]
Sep 11 14:44:45 kernel: fifotest_init
Sep 11 14:44:45 kernel: rtf_create returned: -16
Sep 11 14:44:45 kernel: rtf_put: -16
Sep 11 14:44:48 kernel: fifotest_cleanup
Sep 11 14:44:48 kernel: rtf_destroy returned: -16
I modified my program to check the return value of rtf_create, but I still have
the same problem:
Sep 11 15:15:23 kernel: fifotest_init
Sep 11 15:15:23 kernel: rtf_create returned: 1
Sep 11 15:15:23 kernel: rtf_put: 6
Sep 11 15:15:31 kernel: fifotest_cleanup
Sep 11 15:15:31 kernel: rtf_destroy returned: 0
Sep 11 15:15:33 kernel: fifotest_init
Sep 11 15:15:33 kernel: rtf_create returned: 1
Sep 11 15:15:33 kernel: rtf_put: 6
Sep 11 15:15:35 kernel: fifotest_cleanup
Sep 11 15:15:35 kernel: rtf_destroy returned: 0
Sep 11 15:15:51 kernel: fifotest_init
Sep 11 15:15:51 kernel: rtf_create returned: -12
Sep 11 15:15:51 kernel: could not create FIFO
Sep 11 15:16:05 kernel: fifotest_init
Sep 11 15:16:05 kernel: rtf_create returned: -16
Sep 11 15:16:05 kernel: could not create FIFO
Thanks!
-Jeff
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