100% CPU usage

[Ape]

I got vramfs working nicely, but it continuously uses 100% CPU (one core) after I write something to the filesystem.

Here is a stack trace of the running thread:

#0  0x00007ffff6bb3a87 in sched_yield () from /usr/lib/libc.so.6
#1  0x00007ffff589a15f in ?? () from /usr/lib/libnvidia-opencl.so.1
#2  0x00007ffff59a4ca0 in ?? () from /usr/lib/libnvidia-opencl.so.1
#3  0x00007ffff6e9408c in start_thread () from /usr/lib/libpthread.so.0
#4  0x00007ffff6bcbe7f in clone () from /usr/lib/libc.so.6

[Overv]

Does your OpenCL installation work with other demos?

[Theldus]

Hi,
the exact same thing happens to me (and OpenCL works fine with other applications).
I could see that:

• The 100% of CPU usage depends on the file size and goes away after a while: if few megabytes, it is imperceptible, if 50MB, lasts a few seconds, if 512MB lasts 1 minute and a half until CPU usage drops from 100% to 0%.
• This happens not only in writing, but in reading as well.
• GPU usage seems low while CPU usage remains at 100% (monitored with watch -n0,5 "nvidia-settings -q GPUUtilization -q useddedicatedgpumemory")
• dd returns almost immediately (less than 0.5s for 512M), although CPU usage remains high for quite some time.