search for: copy_user_generic

...this patch but do you have >> any idea how come removing what's supposed to be >> an optimization speeds things up? > With SMAP, the 2x vhost_put_user() will also mean an extra STAC/CLAC pair, > which is probably slower than the overhead of CALL+RET to whatever flavor > of copy_user_generic() gets used. CALL+RET is really the only overhead > since all variants of copy_user_generic() unroll accesses smaller than > 64 bytes, e.g. on a 64-bit system, __copy_to_user() will write all 8 > bytes in a single MOV. > > Removing the special casing also eliminates a few hundred by...

This series tries to access virtqueue metadata through kernel virtual address instead of copy_user() friends since they had too much overheads like checks, spec barriers or even hardware feature toggling. Test shows about 24% improvement on TX PPS. It should benefit other cases as well. Changes from V2: - fix buggy range overlapping check - tear down MMU notifier during vhost ioctl to make sure

This series tries to access virtqueue metadata through kernel virtual address instead of copy_user() friends since they had too much overheads like checks, spec barriers or even hardware feature toggling. Test shows about 24% improvement on TX PPS. It should benefit other cases as well. Changes from V2: - fix buggy range overlapping check - tear down MMU notifier during vhost ioctl to make sure

(The list appears to have eaten my previous attempt to send this. Apologies if you receive multiple copies.) The attached patches allow you to use paravirtualised network and block interfaces from fully virtualised domains, based on Intel''s patches from a few months ago. These are significantly faster than the equivalent ioemu devices, sometimes by more than an order of magnitude.