Re: [Xen-devel] Xen blktap driver for Ceph RBD : Anybody wants to test ? :p

From: Frederik Thuysbaert <frederik.thuysbaert@gmail.com>
To: Sylvain Munaut <s.munaut@whatever-company.com>
Cc: "James Harper" <james.harper@bendigoit.com.au>,
	"Pasi Kärkkäinen" <pasik@iki.fi>,
	"ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [Xen-devel] Xen blktap driver for Ceph RBD : Anybody wants to test ? :p
Date: Wed, 14 Aug 2013 10:43:37 +0200	[thread overview]
Message-ID: <520B4339.6090209@gmail.com> (raw)
In-Reply-To: <CAF6-1L5mcB=Qs3=XpmFC_S2cPWHFaKChYP77ZhLh0+uvWhR3eQ@mail.gmail.com>

On 13-08-13 17:39, Sylvain Munaut wrote:
> Hi,
>
>> I have been testing this a while now, and just finished testing your
>> untested patch. The rbd caching problem still persists.
> Yes, I wouldn't expect to change anything for caching. But I still
> don't understand why caching would change anything at all ... all of
> it should be handled within the librbd lib.
>
>
> Note that I would recommend against caching anyway. The blktap layer
> doesn't pass through the FLUSH commands and so this make it completely
> unsafe because the VM will think things are commited to disk durably
> even though they are not ...
>
>
>
>> I will give the error messages of both dom0 and domU before and after I
>> applied the patch.
> It's actually strange that it changes anything at all.
>
> Can you try adding a ERROR("HERE\n");  in that error path processing
> and check syslog to see if it's triggered at all ?
I did this, and can confirm that it is not triggered.
>
> A traceback would be great if you can get a core file. And possibly
> compile tapdisk with debug symbols.
I'm not quite sure what u mean, can u give some more information on how 
I do this? I compiled tapdisk with ./configure CFLAGS=-g, but I'm not 
sure this is what u meant.
>
> Cheers,
>
>      Sylvain
Regards

- Frederik