From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757204AbbFPVQN (ORCPT ); Tue, 16 Jun 2015 17:16:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55202 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754493AbbFPVQK (ORCPT ); Tue, 16 Jun 2015 17:16:10 -0400 Date: Tue, 16 Jun 2015 23:16:07 +0200 From: "Michael S. Tsirkin" To: Igor Mammedov Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com Subject: Re: [PATCH 0/5] vhost: support upto 509 memory regions Message-ID: <20150616231505-mutt-send-email-mst@redhat.com> References: <1434472419-148742-1-git-send-email-imammedo@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434472419-148742-1-git-send-email-imammedo@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 16, 2015 at 06:33:34PM +0200, Igor Mammedov wrote: > Series extends vhost to support upto 509 memory regions, > and adds some vhost:translate_desc() performance improvemnts > so it won't regress when memslots are increased to 509. > > It fixes running VM crashing during memory hotplug due > to vhost refusing accepting more than 64 memory regions. > > It's only host kernel side fix to make it work with QEMU > versions that support memory hotplug. But I'll continue > to work on QEMU side solution to reduce amount of memory > regions to make things even better. I'm concerned userspace work will be harder, in particular, performance gains will be harder to measure. How about a flag to disable caching? > Performance wise for guest with (in my case 3 memory regions) > and netperf's UDP_RR workload translate_desc() execution > time from total workload takes: > > Memory |1G RAM|cached|non cached > regions # | 3 | 53 | 53 > ------------------------------------ > upstream | 0.3% | - | 3.5% > ------------------------------------ > this series | 0.2% | 0.5% | 0.7% > > where "non cached" column reflects trashing wokload > with constant cache miss. More details on timing in > respective patches. > > Igor Mammedov (5): > vhost: use binary search instead of linear in find_region() > vhost: extend memory regions allocation to vmalloc > vhost: support upto 509 memory regions > vhost: add per VQ memory region caching > vhost: translate_desc: optimization for desc.len < region size > > drivers/vhost/vhost.c | 95 +++++++++++++++++++++++++++++++++++++-------------- > drivers/vhost/vhost.h | 1 + > 2 files changed, 71 insertions(+), 25 deletions(-) > > -- > 1.8.3.1