From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46975) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SmplQ-0001EP-04 for qemu-devel@nongnu.org; Thu, 05 Jul 2012 13:22:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SmplN-0002Ie-Vt for qemu-devel@nongnu.org; Thu, 05 Jul 2012 13:22:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43795) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SmplN-0002IN-OB for qemu-devel@nongnu.org; Thu, 05 Jul 2012 13:22:45 -0400 Message-ID: <4FF5CD5F.1090300@redhat.com> Date: Thu, 05 Jul 2012 20:22:39 +0300 From: Orit Wasserman MIME-Version: 1.0 References: <1341492709-13897-1-git-send-email-owasserm@redhat.com> <1341492709-13897-3-git-send-email-owasserm@redhat.com> <4FF59584.4000303@redhat.com> In-Reply-To: <4FF59584.4000303@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v15 2/9] Add XBZRLE documentation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: peter.maydell@linaro.org, aliguori@us.ibm.com, quintela@redhat.com, stefanha@gmail.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, blauwirbel@gmail.com, avi@redhat.com, pbonzini@redhat.com, chegu_vinod@hp.com On 07/05/2012 04:24 PM, Eric Blake wrote: > On 07/05/2012 06:51 AM, Orit Wasserman wrote: >> Signed-off-by: Orit Wasserman >> --- >> docs/xbzrle.txt | 136 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 files changed, 136 insertions(+), 0 deletions(-) >> create mode 100644 docs/xbzrle.txt >> > >> + >> +Example >> +old buffer: >> +1001 zeros >> +05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 00 00 6b 00 6d >> +3074 zeros > > This _still_ doesn't add up to 4096: > > 1001 + 20 + 3074 = 4095 > >> + >> +new buffer: >> +1001 zeros >> +01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 00 67 00 69 >> +3704 zeros > > Still a transposition error. > > Also, this still has the flaw that it is too weak of an example - the > only unchanged bytes happen to also be zero bytes to begin with; it > would be much nicer if the example included at least one non-zero byte > that did not change between old and new. > >> + >> +encoded buffer: >> + >> +encoded length 24 >> +e9 07 0f 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 03 01 67 01 01 69 > ^^ > That says you have a zrun of 3 bytes, but the example only shows a zrun > of 2 bytes. > > It feels like I'm pulling teeth to get a good example. If you will just > squash in the following (hand-written) diff below, you will then have > 4096 bytes in both old and new buffers, and your encoded buffer listing > a zrun of 3 will be correct, plus you will be demonstrating a non-zero > byte that remained unchanged. > > @@ ???,??? @@ > Example > old buffer: > 1001 zeros > -05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 00 00 6b 00 6d > +05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 68 00 00 6b 00 6d > 3074 zeros > > new buffer: > 1001 zeros > -01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 00 67 00 69 > -3704 zeros > +01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 68 00 00 67 00 69 > +3074 zeros > > encoded buffer: > I will use this example , thanks, Orit