search for: unsafe_copy_xxx_us

On 2018/12/13 ??11:27, Michael S. Tsirkin wrote: > On Thu, Dec 13, 2018 at 06:10:19PM +0800, Jason Wang wrote: >> Hi: >> >> 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. > Userspace accesses

On 2018/12/13 ??11:27, Michael S. Tsirkin wrote: > On Thu, Dec 13, 2018 at 06:10:19PM +0800, Jason Wang wrote: >> Hi: >> >> 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. > Userspace accesses

...er the unexpected amount of work and in the best case it can give the same performance to vmap(). I'm not sure it's worth. > >> - unsafe_put_user/unsafe_get_user is not sufficient for accessing structures >> (e.g accessing descriptor) or arrays (batching). > So you want unsafe_copy_xxx_user? I can do this. Hang on will post. > >> - Unless we can batch at least the accessing of two places in three of >> avail, used and descriptor in one run. There will be no difference. E.g we >> can batch updating used ring, but it won't make any difference in this case. &gt...

...er the unexpected amount of work and in the best case it can give the same performance to vmap(). I'm not sure it's worth. > >> - unsafe_put_user/unsafe_get_user is not sufficient for accessing structures >> (e.g accessing descriptor) or arrays (batching). > So you want unsafe_copy_xxx_user? I can do this. Hang on will post. > >> - Unless we can batch at least the accessing of two places in three of >> avail, used and descriptor in one run. There will be no difference. E.g we >> can batch updating used ring, but it won't make any difference in this case. &gt...

...nt, it won't have any difference for the rest of > architecture. Is there an issue on other architectures? If yes they can be extended there. > - unsafe_put_user/unsafe_get_user is not sufficient for accessing structures > (e.g accessing descriptor) or arrays (batching). So you want unsafe_copy_xxx_user? I can do this. Hang on will post. > - Unless we can batch at least the accessing of two places in three of > avail, used and descriptor in one run. There will be no difference. E.g we > can batch updating used ring, but it won't make any difference in this case. > So let's...

...in the best case it can give the > same performance to vmap(). I'm not sure it's worth. > > > > > > > - unsafe_put_user/unsafe_get_user is not sufficient for accessing structures > > > (e.g accessing descriptor) or arrays (batching). > > So you want unsafe_copy_xxx_user? I can do this. Hang on will post. > > > > > - Unless we can batch at least the accessing of two places in three of > > > avail, used and descriptor in one run. There will be no difference. E.g we > > > can batch updating used ring, but it won't make any diff...