Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757965Ab2FENJy (ORCPT ); Tue, 5 Jun 2012 09:09:54 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:36654 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751392Ab2FENJw (ORCPT ); Tue, 5 Jun 2012 09:09:52 -0400 From: Nikunj A Dadhania To: Stefano Stabellini , "peterz\@infradead.org" Cc: Stefano Stabellini , "mingo\@elte.hu" , "mtosatti\@redhat.com" , "avi\@redhat.com" , "raghukt\@linux.vnet.ibm.com" , "kvm\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , "x86\@kernel.org" , "jeremy\@goop.org" , "vatsa\@linux.vnet.ibm.com" , "hpa\@zytor.com" , Konrad Rzeszutek Wilk Subject: Re: [PATCH v2 6/7] kvm,x86: RCU based table free In-Reply-To: References: <20120604050223.4560.2874.stgit@abhimanyu.in.ibm.com> <20120604050822.4560.54662.stgit@abhimanyu.in.ibm.com> <87ehpuqam8.fsf@linux.vnet.ibm.com> User-Agent: Notmuch/0.10.2+70~gf0e0053 (http://notmuchmail.org) Emacs/24.0.95.1 (x86_64-unknown-linux-gnu) Date: Tue, 05 Jun 2012 18:34:31 +0530 Message-ID: <878vg1rjts.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain x-cbid: 12060502-0260-0000-0000-0000014C63EF Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2734 Lines: 72 On Tue, 5 Jun 2012 12:58:32 +0100, Stefano Stabellini wrote: > On Tue, 5 Jun 2012, Nikunj A Dadhania wrote: > > On Tue, 5 Jun 2012 11:48:02 +0100, Stefano Stabellini wrote: > > > > > > I am also interested in introducing HAVE_RCU_TABLE_FREE on x86 for Xen. > > > Maybe we can pull our efforts together :-) > > > > > > Giving a look at this patch, it doesn't look like it is introducing > > > CONFIG_HAVE_RCU_TABLE_FREE anywhere under arch/x86. > > > How is the user supposed to set it? > > > > > I am doing that in the next patch only for KVM-ParavirtTLB flush, as > > there is a bug in this implementation that patch [7/7] fixes. > > > > Refer following thread for details: > > http://mid.gmane.org/1337254086.4281.26.camel@twins > > http://mid.gmane.org/1337273959.4281.62.camel@twins > > Thanks, somehow I missed the 7/7 patch. > > From the Xen POV, your patch is fine because we'll just select > PARAVIRT_TLB_FLUSH on CONFIG_XEN (see appended patch for completeness). > Selecting ARCH_HW_WALKS_PAGE_TABLE in place of PARAVIRT_TLB_FLUSH should suffice. > The main difference between the two approaches is that a kernel with > PARAVIRT_TLB_FLUSH and/or CONFIG_XEN enabled is going to have > HAVE_RCU_TABLE_FREE even when running on native. > > Are you proposing this series for 3.5? > If not (because it depends on ticketlocks and KVM Paravirt Spinlock > patches), > 3.6 I suppose as the merge window is already closed and we are having some discussions on PLE results. > could you extract patch 6/7 and 7/7 and send them out > separately? > > I am saying this because Xen needs the HAVE_RCU_TABLE_FREE fix even if > pv ticketlock are not accepted. This is an outstanding bug for us > unfortunately. > PeterZ has a patch in his tlb-unify: mm, x86: Add HAVE_RCU_TABLE_FREE support Implements optional HAVE_RCU_TABLE_FREE support for x86. This is useful for things like Xen and KVM where paravirt tlb flush means the software page table walkers like GUP-fast cannot rely on IRQs disabling like regular x86 can. Cc: Nikunj A Dadhania Cc: Jeremy Fitzhardinge Cc: Avi Kivity Signed-off-by: Peter Zijlstra http://git.kernel.org/?p=linux/kernel/git/peterz/mmu.git;a=commit;h=8a7e6fa5be9d2645c3394892c870113e6e5d9309 PeterZ, is 7/7 alright to be picked? Regards Nikunj -- 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/