From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 23 May 2006 14:40:01 -0700 (PDT) From: Christoph Lameter Subject: update_mmu_cache vs. lazy_mmu_prot_update In-Reply-To: <000001c67eae$3e29bd90$e734030a@amr.corp.intel.com> Message-ID: References: <000001c67eae$3e29bd90$e734030a@amr.corp.intel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Chen, Kenneth W" Cc: 'Hugh Dickins' , Peter Zijlstra , Andrew Morton , Linus Torvalds , David Howells , Rohit Seth , linux-mm@kvack.org, agl@us.ibm.com, linux-ia64@vger.kernel.org List-ID: On Tue, 23 May 2006, Chen, Kenneth W wrote: > > Except that, instead of agreeing it should be renamed, I say it should > > be deleted entirely. It seems to represent that ia64 has an empty > > update_mmu_cache, and someone decided to add a new interface instead > > of giving ia64 that work to do in its update_mmu_cache. > > My memory recollects that it was done just like what you suggested: > overloading update_mmu_cache for ia64, but it was vetoed by several mm > experts. And as a result a new function was introduced. lazy_mmu_prot_update is always called after update_mmu_cache except when we change permissions (hugetlb_change_protection() and change_pte_range()). So if we conflate those two then arches may have to be updated to avoid flushing the mmu if we only modified protections. I think update_mmu_cache() should be dropped in page_wrprotect_one() in order to be consistent scheme. And avoiding mmu flushes will increase the performance of page_wrprotect_one.. lazy_mmu_prot_update must be there since we are changing permissions. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org