From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53584) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YLJ6h-00014O-0A for qemu-devel@nongnu.org; Tue, 10 Feb 2015 17:16:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YLJ6g-0008E3-95 for qemu-devel@nongnu.org; Tue, 10 Feb 2015 17:16:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56265) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YLJ6g-0008Di-0A for qemu-devel@nongnu.org; Tue, 10 Feb 2015 17:16:34 -0500 Message-ID: <54DA833E.30103@redhat.com> Date: Tue, 10 Feb 2015 17:16:30 -0500 From: Max Reitz MIME-Version: 1.0 References: <1423532117-14490-1-git-send-email-jsnow@redhat.com> <1423532117-14490-5-git-send-email-jsnow@redhat.com> In-Reply-To: <1423532117-14490-5-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 v12 04/17] hbitmap: add hbitmap_merge List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, armbru@redhat.com, vsementsov@parallels.com, stefanha@redhat.com On 2015-02-09 at 20:35, 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 | 11 +++++++++++ > util/hbitmap.c | 32 ++++++++++++++++++++++++++++++++ > 2 files changed, 43 insertions(+) Reviewed-by: Max Reitz