Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755355Ab0GAMRe (ORCPT ); Thu, 1 Jul 2010 08:17:34 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:55268 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751407Ab0GAMRd (ORCPT ); Thu, 1 Jul 2010 08:17:33 -0400 Message-ID: <4C2C8674.4080607@cn.fujitsu.com> Date: Thu, 01 Jul 2010 20:13:40 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , LKML , KVM list Subject: Re: [PATCH v3 9/11] KVM: MMU: prefetch ptes when intercepted guest #PF References: <4C2AF9FA.9020601@cn.fujitsu.com> <4C2AFB65.2030807@cn.fujitsu.com> <20100630204324.GA5366@amt.cnet> <4C2BEB48.3080705@cn.fujitsu.com> <4C2C85E6.1050303@redhat.com> In-Reply-To: <4C2C85E6.1050303@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1395 Lines: 41 Avi Kivity wrote: > On 07/01/2010 04:11 AM, Xiao Guangrong wrote: >> >> Marcelo Tosatti wrote: >> >> >>>> + >>>> + addr = gfn_to_hva_many(vcpu->kvm, gfn,&entry); >>>> + if (kvm_is_error_hva(addr)) >>>> + return -1; >>>> + >>>> + entry = min(entry, (int)(end - start)); >>>> + ret = __get_user_pages_fast(addr, entry, 1, pages); >>>> + if (ret<= 0) >>>> + return -1; >>>> >>> Why can't you use gfn_to_pfn_atomic() here, one page at a time? Is >>> the overhead significant that this is worthwhile? >>> >>> You're bypassing the centralized interface. >>> >> I think it's worthwhile to do since we can reduce gup overhead, no reason >> to traverse process's page table again and again for the consecutive >> pages. >> > > Then we should make the centralized interface work in terms of multiple > pages, and write the single-page interfaces in terms of the multipage > interfaces. > Umm, i'll import a new function named gfn_to_pfn_many_atomic(... int *enough), using 'enough' to indicate whether have got the all consecutive pages in the slot, Marcelo, how about it? :-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/