From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [patch 2/2]: introduce fast_gup Date: Thu, 17 Apr 2008 09:18:52 -0700 (PDT) Message-ID: References: <20080328025455.GA8083@wotan.suse.de> <20080328030023.GC8083@wotan.suse.de> <1208444605.7115.2.camel@twins> <1208448768.7115.30.camel@twins> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <1208448768.7115.30.camel@twins> Sender: linux-arch-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: To: Peter Zijlstra Cc: Nick Piggin , Andrew Morton , shaggy-V7BBcbaFuwjMbYB6QlFGEg@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Clark Williams , Ingo Molnar , Jeremy Fitzhardinge On Thu, 17 Apr 2008, Peter Zijlstra wrote: > > Jeremy, did I get the paravirt stuff right? I don't think this is worth it to virtualize. We access the page tables directly in any number of places, having a "get_pte()" indirection here is not going to help anything. Just make it an x86-only inline function. In fact, you can keep it inside arch/x86/mm/gup.c, because nobody else is likely to ever even need it, since normal accesses are all supposed to be done under the page table spinlock, so they do not have this issue at all. The indirection and virtualization thing is just going to complicate matters for no good reason. Linus From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:55577 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764788AbYDQQUf (ORCPT ); Thu, 17 Apr 2008 12:20:35 -0400 Date: Thu, 17 Apr 2008 09:18:52 -0700 (PDT) From: Linus Torvalds Subject: Re: [patch 2/2]: introduce fast_gup In-Reply-To: <1208448768.7115.30.camel@twins> Message-ID: References: <20080328025455.GA8083@wotan.suse.de> <20080328030023.GC8083@wotan.suse.de> <1208444605.7115.2.camel@twins> <1208448768.7115.30.camel@twins> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Nick Piggin , Andrew Morton , shaggy@austin.ibm.com, axboe@kernel.dk, linux-mm@kvack.org, linux-arch@vger.kernel.org, Clark Williams , Ingo Molnar , Jeremy Fitzhardinge Message-ID: <20080417161852.ug6WDfdkjW4ZcP8kcJ-MxRY0CNOKQIagmGb67S8FEFM@z> On Thu, 17 Apr 2008, Peter Zijlstra wrote: > > Jeremy, did I get the paravirt stuff right? I don't think this is worth it to virtualize. We access the page tables directly in any number of places, having a "get_pte()" indirection here is not going to help anything. Just make it an x86-only inline function. In fact, you can keep it inside arch/x86/mm/gup.c, because nobody else is likely to ever even need it, since normal accesses are all supposed to be done under the page table spinlock, so they do not have this issue at all. The indirection and virtualization thing is just going to complicate matters for no good reason. Linus