From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 0/2] Simplify RCU freeing of shadow pages Date: Fri, 20 Apr 2012 23:31:32 -0300 Message-ID: <20120421023132.GA18062@amt.cnet> References: <1334852797-28167-1-git-send-email-avi@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, Xiao Guangrong To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50975 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754651Ab2DUCgU (ORCPT ); Fri, 20 Apr 2012 22:36:20 -0400 Content-Disposition: inline In-Reply-To: <1334852797-28167-1-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Apr 19, 2012 at 07:26:35PM +0300, Avi Kivity wrote: > This patchset simplifies the freeing by RCU of mmu pages. > > Xiao, I'm sure you thought of always freeing by RCU. Why didn't you choose > this way? I saves a couple of atomics in the fast path. > > Avi Kivity (2): > KVM: MMU: Always free shadow pages using RCU > KVM: MMU: Recover space used by rcu_head in struct kvm_mmu_page > > arch/x86/include/asm/kvm_host.h | 9 +++--- > arch/x86/kvm/mmu.c | 58 ++++++++------------------------------- > 2 files changed, 15 insertions(+), 52 deletions(-) Check Documentation/RCU/checklist.txt item 8. a. Keeping a count of the number of data-structure elements used by the RCU-protected data structure, including those waiting for a grace period to elapse. Enforce a limit on this number, stalling updates as needed to allow previously deferred frees to complete. Alternatively, limit only the number awaiting deferred free rather than the total number of elements.