> > Thanks for doing this implementation! One reason usercopy hardening
> > didn't persue doing a "full" stacktrace was because it seemed relatively
> > expensive. Did you do any usercopy-heavily workload testing to see if
> > there was a noticeable performance impact?
Look at anything that uses sendmsg().
It is noticeably more expensive than sendto().
All the extra copy_from_user() cause measurable slow slowdowns.
Using __copy_from_user()(to avoid 'hardending') in the socket code
and when reading the iov[] gives a measurable improvement.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT,
UK
Registration No: 1397386 (Wales)
