From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:47607)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <quintela@redhat.com>) id 1SfsvY-0001Zy-Lw
	for qemu-devel@nongnu.org; Sat, 16 Jun 2012 09:20:33 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <quintela@redhat.com>) id 1SfsvW-0005YG-Rs
	for qemu-devel@nongnu.org; Sat, 16 Jun 2012 09:20:32 -0400
Received: from mx1.redhat.com ([209.132.183.28]:53018)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <quintela@redhat.com>) id 1SfsvW-0005Y5-Jn
	for qemu-devel@nongnu.org; Sat, 16 Jun 2012 09:20:30 -0400
From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <20120616094827.GL23851@valinux.co.jp> (Isaku Yamahata's message
	of "Sat, 16 Jun 2012 18:48:27 +0900")
References: <cover.1338802190.git.yamahata@valinux.co.jp>
	<cover.1338802190.git.yamahata@valinux.co.jp>
	<77d2fc4b1c99e1520a7fbe873e73119ce9463592.1338802192.git.yamahata@valinux.co.jp>
	<87vcitshm6.fsf@elfo.mitica> <20120616094827.GL23851@valinux.co.jp>
Date: Sat, 16 Jun 2012 15:19:57 +0200
Message-ID: <87vcircs1u.fsf@elfo.mitica>
MIME-Version: 1.0
Content-Type: text/plain
Subject: Re: [Qemu-devel] [PATCH v2 35/41] postcopy: introduce helper
	functions for postcopy
Reply-To: quintela@redhat.com
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Isaku Yamahata <yamahata@valinux.co.jp>
Cc: benoit.hudzia@gmail.com, aarcange@redhat.com, aliguori@us.ibm.com, kvm@vger.kernel.org, satoshi.itoh@aist.go.jp, stefanha@gmail.com, t.hirofuchi@aist.go.jp, dlaor@redhat.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, yoshikawa.takuya@oss.ntt.co.jp, owasserm@redhat.com, avi@redhat.com, pbonzini@redhat.com

Isaku Yamahata <yamahata@valinux.co.jp> wrote:
> On Thu, Jun 14, 2012 at 11:34:09PM +0200, Juan Quintela wrote:

>> > +size_t umem_pages_size(uint64_t nr)
>> > +{
>> > +    return sizeof(struct umem_pages) + nr * sizeof(uint64_t);
>> 
>> Can we make sure that the pgoffs field is aligned?  I know that as it is
>> now it is aligned, but better to be sure?
>
> It is already done by gcc extension, zero length array.

Ah, I didn't knew that propierty of the zero arrays extension.  thanks.

>> 
>> Grr, we don't have a function that writes does a "safe_write".  The most
>> similar thing in qemu looks to be send_all().
>
> So we should introduce something like qemu_safe_write/read?

I guess so.  If you look around, you will see that we have a lot of
cases where we have this pattern.  But that is not a problem ofthis
patch, was already there.

>
>> Talking about looking, what protects that no other thread enters this
>> function before this one calls madvise?   Or I am losing something obvious?
>
> It is assumed that only main thread calls this function via iohandler.

Ok.  Can we add a comment then?

Later, Juan.