Re: LFENCE instruction (was: [rfc][patch 3/3] x86: optimise barriers)

2007-10-17 Thread Nick Piggin
On Wed, Oct 17, 2007 at 01:51:17PM +0800, Herbert Xu wrote: > Nick Piggin <[EMAIL PROTECTED]> wrote: > > > > Also, for non-wb memory. I don't think the Intel document referenced > > says anything about this, but the AMD document says that loads can pass > > loads (page 8, rule b). > > > > This is

Re: LFENCE instruction (was: [rfc][patch 3/3] x86: optimise barriers)

2007-10-16 Thread Herbert Xu
Nick Piggin <[EMAIL PROTECTED]> wrote: > > Also, for non-wb memory. I don't think the Intel document referenced > says anything about this, but the AMD document says that loads can pass > loads (page 8, rule b). > > This is why our rmb() is still an lfence. BTW, Xen (in particular, the code in dr