From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53083) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eKMvd-0005B6-Sa for qemu-devel@nongnu.org; Thu, 30 Nov 2017 06:22:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eKMva-0003iD-Of for qemu-devel@nongnu.org; Thu, 30 Nov 2017 06:22:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16462) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eKMva-0003ci-J5 for qemu-devel@nongnu.org; Thu, 30 Nov 2017 06:22:50 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0A16D80480 for ; Thu, 30 Nov 2017 11:22:49 +0000 (UTC) Date: Thu, 30 Nov 2017 12:22:45 +0100 From: Igor Mammedov Message-ID: <20171130122245.7e713d2f@redhat.com> In-Reply-To: <20171129185026.23632-1-dgilbert@redhat.com> References: <20171129185026.23632-1-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC 0/7] Rework vhost memory region updates List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" Cc: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, mst@redhat.com On Wed, 29 Nov 2017 18:50:19 +0000 "Dr. David Alan Gilbert (git)" wrote: > From: "Dr. David Alan Gilbert" > > Hi, > This is an experimental set that reworks the way the vhost > code handles changes in physical address space layout that > came from a discussion with Igor. Thanks for looking into it. > Instead of updating and trying to merge sections of address > space on each add/remove callback, we wait until the commit phase > and go through and rebuild a list by walking the Flatview of > memory and end up producing an ordered list. > We compare the list to the old list to trigger updates. > > Note, only very lightly tested so far, I'm just trying to see if it's > the right shape. > > Igor, is this what you were intending? I was thinking about a little less intrusive approach where vhost_region_add/del are modified to maintain sorted by GPA array of mem_sections, vhost_dev::mem is dropped altogether and vhost_memory_region array is build/used/freed on every vhost_commit(). Maintaining sorted array should roughly cost us O(2 log n) if binary search is used. However I like your idea with iterator even more as it have potential to make it even faster O(n) if we get rid of quadratic and relatively complex vhost_update_compare_list(). Pls, see comments on individual patches. > Dave > > Dr. David Alan Gilbert (7): > memory: address_space_iterate > vhost: Move log_dirty check > vhost: New memory update functions > vhost: update_mem_cb implementation > vhost: Compare new and old memory lists > vhost: Copy updated region data into device state > vhost: Remove vhost_set_memory and children > > hw/virtio/trace-events | 8 + > hw/virtio/vhost.c | 424 ++++++++++++++++++++++--------------------------- > include/exec/memory.h | 23 +++ > memory.c | 22 +++ > 4 files changed, 241 insertions(+), 236 deletions(-) >