From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37530) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aXndf-0006qz-DG for qemu-devel@nongnu.org; Mon, 22 Feb 2016 05:22:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aXndZ-000509-92 for qemu-devel@nongnu.org; Mon, 22 Feb 2016 05:22:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35487) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aXndZ-0004zv-43 for qemu-devel@nongnu.org; Mon, 22 Feb 2016 05:22:41 -0500 References: <1456130097-4208-1-git-send-email-arei.gonglei@huawei.com> From: Paolo Bonzini Message-ID: <56CAE16C.3060800@redhat.com> Date: Mon, 22 Feb 2016 11:22:36 +0100 MIME-Version: 1.0 In-Reply-To: <1456130097-4208-1-git-send-email-arei.gonglei@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 0/3] memory: an optimization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gonglei , qemu-devel@nongnu.org Cc: peter.huangpeng@huawei.com On 22/02/2016 09:34, Gonglei wrote: > Perf top tells me qemu_get_ram_ptr consume some cpu cycles. > > Before this optimization: > 1.26% qemu-kvm [.] qemu_get_ram_ptr > 0.89% qemu-kvm [.] qemu_get_ram_block > > Applied the patch set: > 0.87% qemu-kvm [.] qemu_get_ram_ptr > > And Paolo suggested that we can get rid of qemu_get_ram_ptr > by storing the RAMBlock pointer into the memory region, > instead of the ram_addr_t value. And after appling this change, > I got much better performance indeed. > > BTW, PATCH 3 is an occasional find. > > v2: > - using 'struct RAMBlock *' instead of 'void *' in patch 1 [Fam] > - drop superfluous comments in patch 1 [Fam] > > Gonglei (3): > exec: store RAMBlock pointer into memory region > memory: optimize qemu_get_ram_ptr and qemu_ram_ptr_length > memory: Remove the superfluous code > > exec.c | 48 ++++++++++++++++++++++++++++++------------------ > include/exec/memory.h | 8 ++++---- > memory.c | 3 ++- > 3 files changed, 36 insertions(+), 23 deletions(-) > Thanks Lei and Fam, patches queued. Paolo