Re: [PATCH v1 0/8] VFS: In-kernel copy system call

On Fri, Sep 04, 2015 at 04:25:27PM -0600, Andreas Dilger wrote:

This is a bit of a surprising result, since in my testing in the
past, copy_{to/from}_user() is a major consumer of CPU time (50%
of a CPU core at 1GB/s).  What backing filesystem did you test on?

While we are at it, was cp(1) using read(2)/write(2) loop or was it using
something else (sendfile(2), for example)?