From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH v5 0/9] KVM: fast page fault Date: Thu, 24 May 2012 14:31:38 +0800 Message-ID: <4FBDD5CA.9020906@linux.vnet.ibm.com> References: <4FBCA4FB.8050501@linux.vnet.ibm.com> <4FBCCC09.3020605@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Avi Kivity Return-path: Received: from e28smtp03.in.ibm.com ([122.248.162.3]:60934 "EHLO e28smtp03.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163Ab2EXGcX (ORCPT ); Thu, 24 May 2012 02:32:23 -0400 Received: from /spool/local by e28smtp03.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 24 May 2012 12:01:45 +0530 In-Reply-To: <4FBCCC09.3020605@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/23/2012 07:37 PM, Avi Kivity wrote: > On 05/23/2012 11:51 AM, Xiao Guangrong wrote: >> Changlog: >> This are some changes from Marcelo's review: >> - drop SPTE_WRITE_PROTECT bit, now, only one bit is needed to do >> lockless update. >> >> - always atomicly update spte if it can be updated out of mmu-lock. >> >> - flod the judgement of tlb flush into mmu_spte_update(), make the >> code easilyer audited. >> >> Performance result: >> - autoest migration test (smp2.Fedora.16.64.migrate.with_autotest.dbench.unix): >> before after >> smp2.Fedora.16.64.migrate.unix 93 91 +2.1% >> smp2.Fedora.16.64.migrate.with_autotest.dbench.unix 218 188 +13.7% >> >> - the benchmark attached is used to measure the resuming time >> after dirty-log >> before after >> Run 10 times, Avg time: 512466818 ns. 269231261 ns +47.5% > > Still scary (esp. indirect sptes), but looks pretty good. Hmm, i do not have a better way to solve the ABA problem on indirect spte now. :( How about only allow fast page fault to work for direct spte?