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Writing Linux Kernel Functions In CUDA With KGPU
An anonymous reader writes "Until today, GPGPU computing was a userspace privilege because of NVIDIA's closed-source policy and AMD's semi-open state. KGPU is a workaround to enable Linux kernel functionality written in CUDA. Instead of figuring out GPU specs via reverse-engineering, it simply uses a userspace helper to do CUDA-related work for kernelspace requesters. A demo in its current source repository is a modified eCryptfs, which is an encrypted filesystem used by Ubuntu and other distributions. With the accelerated performance of a GPU AES cipher in the Linux kernel, eCryptfs can get a 3x uncached read speedup and near 4x write speedup on an Intel X25-M 80G SSD. However, both the GPU cipher-based eCryptfs and the CPU cipher-based one are changed to use ECB cipher mode for parallelism. A CTR, counter mode, cipher may be much more secure, although the real vanilla eCryptfs uses CBC mode. Anyway, GPU vendors should think about opening their drivers and computing libraries, or at least providing a mechanism to make it easy to do GPU computing inside an OS kernel, given the fact that GPUs are so widely deployed and the potential future of heterogeneous operating systems."
GTFO!
This is what should be on slashdot, not stories about the latest iphone.
As opposed to having them done by my Intel CPU, for which Intel has helpfully provided full schematics.
You are awash in a sea of fiercely stated opinions. Obvious exits are: 'File->Quit', 'Reply', and 'Page Down'.
There are also other concerns than the context switch overhead...particularly when dealing with filesystems or data storage devices.
For instance, suppose part of your userspace daemon gets swapped out, and you now need to upcall to userspace. That part that got paged out then has to be paged back in. If memory is tight, then the kernel may have to free some memory, and it may decide to flush out dirty data to the filesystem or device that is dependent on the userspace daemon. At that point, you're effectively deadlocked.
Most of those sorts of problems can be overcome with careful coding and making sure the important parts of the daemon are mlocked, but you do have to be careful and it's not always straightforward to do that.