From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Wed, 29 Mar 2006 07:44:05 +0000 Subject: RE: Prefetch mmap_sem in ia64_do_page_fault() Message-Id: <200603290743.k2T7hKg04228@unix-os.sc.intel.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Chen, Kenneth W wrote on Tuesday, March 28, 2006 11:32 PM > Christoph Lameter wrote on Tuesday, March 28, 2006 11:16 PM > > > > I saw David Mosberger's patch from last year > > > > and it seems that he implemented fast handling of these NULL cases? > > I know about that patch and I'm referring in the context of that commit: > > ld8.s r1=[r0] - immediate nat generation, no fault > lfetch.fault [r0] - generate nat page consumption because lfetch is not > considered as a speculative access. > > The nat page consumption fault handler should be rather quick, though cpu > still have to fault into the handler, muck around with ipsr.ed bit and > then rfi. What I'm saying is there is an even *faster* way of doing > prefetch. One other caveat with this is that if you have a tlb miss on mm->mmap_sem, it won't prefetch anything because alt_dtlb_miss handler will nuke the ld8.s or lfetch instruction :-( - Ken