From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: [PATCH net-next v5 4/9] xen-netback: Change RX path for mapped SKB fragments Date: Thu, 27 Feb 2014 16:01:41 +0000 Message-ID: <20140227160141.GJ16241@zion.uk.xensource.com> References: <1390253069-25507-1-git-send-email-zoltan.kiss@citrix.com> <1390253069-25507-5-git-send-email-zoltan.kiss@citrix.com> <1392745532.23084.65.camel@kazak.uk.xensource.com> <53093051.9040907@citrix.com> <530B4E05.4020900@schaman.hu> <530B606F.2070902@citrix.com> <20140227124327.GD16241@zion.uk.xensource.com> <530F5E9B.5020404@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Wei Liu , Ian Campbell , , , , To: Zoltan Kiss Return-path: Content-Disposition: inline In-Reply-To: <530F5E9B.5020404@citrix.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Feb 27, 2014 at 03:49:47PM +0000, Zoltan Kiss wrote: > On 27/02/14 12:43, Wei Liu wrote: > >On Mon, Feb 24, 2014 at 03:08:31PM +0000, Zoltan Kiss wrote: > >>On 24/02/14 13:49, Zoltan Kiss wrote: > >>>On 22/02/14 23:18, Zoltan Kiss wrote: > >>>>On 18/02/14 17:45, Ian Campbell wrote: > >>>>>On Mon, 2014-01-20 at 21:24 +0000, Zoltan Kiss wrote: > >>>>> > >>>>>Re the Subject: change how? Perhaps "handle foreign mapped pages on the > >>>>>guest RX path" would be clearer. > >>>>Ok, I'll do that. > >>>> > >>>>> > >>>>>>RX path need to know if the SKB fragments are stored on > >>>>>>pages from another > >>>>>>domain. > >>>>>Does this not need to be done either before the mapping change > >>>>>or at the > >>>>>same time? -- otherwise you have a window of a couple of commits where > >>>>>things are broken, breaking bisectability. > >>>>I can move this to the beginning, to keep bisectability. I've > >>>>put it here originally because none of these makes sense without > >>>>the previous patches. > >>>Well, I gave it a close look: to move this to the beginning as a > >>>separate patch I would need to put move a lot of definitions from > >>>the first patch to here (ubuf_to_vif helper, > >>>xenvif_zerocopy_callback etc.). That would be the best from bisect > >>>point of view, but from patch review point of view even worse than > >>>now. So the only option I see is to merge this with the first 2 > >>>patches, so it will be even bigger. > >>Actually I was stupid, we can move this patch earlier and introduce > >>stubs for those 2 functions. But for the another two patches (#6 and > >>#8) it's still true that we can't move them before, only merge them > >>into the main, as they heavily rely on the main patch. #6 is > >>necessary for Windows frontends, as they are keen to send too many > >>slots. #8 is quite a rare case, happens only if a guest wedge or > >>malicious, and sits on the packet. > >>So my question is still up: do you prefer perfect bisectability or > >>more segmented patches which are not that pain to review? > >> > > > >What's the diff stat if you merge those patches? > > > > drivers/net/xen-netback/common.h | 33 ++- > drivers/net/xen-netback/interface.c | 67 +++++- > drivers/net/xen-netback/netback.c | 424 > ++++++++++++++++++++++------------- > 3 files changed, 362 insertions(+), 162 deletions(-) Not terribly bad IMHO -- if you look at netback's changelog, I've done worse. :-P