From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58814) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YkxQX-00050q-S8 for qemu-devel@nongnu.org; Wed, 22 Apr 2015 12:23:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YkxQT-0000oX-1Z for qemu-devel@nongnu.org; Wed, 22 Apr 2015 12:23:05 -0400 Message-ID: <5537CADF.6070800@redhat.com> Date: Wed, 22 Apr 2015 18:22:55 +0200 From: Max Reitz MIME-Version: 1.0 References: <1429314609-29776-1-git-send-email-jsnow@redhat.com> <1429314609-29776-8-git-send-email-jsnow@redhat.com> In-Reply-To: <1429314609-29776-8-git-send-email-jsnow@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 07/21] hbitmap: add hbitmap_merge List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , qemu-block@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, vsementsov@parallels.com, stefanha@redhat.com On 18.04.2015 01:49, John Snow wrote: > We add a bitmap merge operation to assist in error cases > where we wish to combine two bitmaps together. > > This is algorithmically O(bits) provided HBITMAP_LEVELS remains > constant. For a full bitmap on a 64bit machine: > sum(bits/64^k, k, 0, HBITMAP_LEVELS) ~= 1.01587 * bits > > We may be able to improve running speed for particularly sparse > bitmaps by using iterators, but the running time for dense maps > will be worse. > > We present the simpler solution first, and we can refine it later > if needed. > > Signed-off-by: John Snow > --- > include/qemu/hbitmap.h | 13 +++++++++++++ > util/hbitmap.c | 33 +++++++++++++++++++++++++++++++++ > 2 files changed, 46 insertions(+) Reviewed-by: Max Reitz