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

From: James Harper <james.harper@bendigoit.com.au>
To: Sylvain Munaut <s.munaut@whatever-company.com>
Cc: "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: Tue, 13 Aug 2013 21:47:38 +0000	[thread overview]
Message-ID: <6035A0D088A63A46850C3988ED045A4B63896729@BITCOM1.int.sbss.com.au> (raw)
In-Reply-To: <CAF6-1L6jJvYuHN+BoucU2RNzv2R9dpMhbD1UVF96mBPO25FM5g@mail.gmail.com>

Just noticed email subject "qemu-1.4.0 and onwards, linux kernel 3.2.x, ceph-RBD, heavy I/O leads to kernel_hung_tasks_timout_secs message and unresponsive qemu-process, [Qemu-devel] [Bug 1207686]" where Sage noted that he has seen a completion called twice in the logs the OP posted. If that is actually happening (and not just an artefact of logging ring buffer overflowing or something) then I think that could easily cause a segfault in tapdisk rbd.

I'll try and see if I can log when that happens.

James

> -----Original Message-----
> From: Sylvain Munaut [mailto:s.munaut@whatever-company.com]
> Sent: Tuesday, 13 August 2013 7:20 PM
> To: James Harper
> Cc: Pasi Kärkkäinen; ceph-devel@vger.kernel.org; xen-devel@lists.xen.org
> Subject: Re: [Xen-devel] Xen blktap driver for Ceph RBD : Anybody wants to
> test ? :p
> 
> Hi,
> 
> > I hope not. How could I tell? It's not something I've explicitly enabled.
> 
> It's disabled by default.
> 
> So you'd have to have enabled it either in ceph.conf  or directly in
> the device path in the xen config. (option is 'rbd cache',
> http://ceph.com/docs/next/rbd/rbd-config-ref/ )
> 
> Cheers,
> 
>     Sylvain
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