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d="scan'208";a="9932140" Date: Thu, 12 Dec 2019 12:46:16 +0100 From: Roger Pau =?iso-8859-1?Q?Monn=E9?= To: Paul Durrant CC: , , , Konrad Rzeszutek Wilk , Jens Axboe , Boris Ostrovsky , Juergen Gross , "Stefano Stabellini" Subject: Re: [PATCH v3 4/4] xen-blkback: support dynamic unbind/bind Message-ID: <20191212114616.GC11756@Air-de-Roger> References: <20191211152956.5168-1-pdurrant@amazon.com> <20191211152956.5168-5-pdurrant@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191211152956.5168-5-pdurrant@amazon.com> X-ClientProxiedBy: AMSPEX02CAS01.citrite.net (10.69.22.112) To AMSPEX02CL03.citrite.net (10.69.22.127) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 11, 2019 at 03:29:56PM +0000, Paul Durrant wrote: > By simply re-attaching to shared rings during connect_ring() rather than > assuming they are freshly allocated (i.e assuming the counters are zero) > it is possible for vbd instances to be unbound and re-bound from and to > (respectively) a running guest. > > This has been tested by running: > > while true; > do fio --name=randwrite --ioengine=libaio --iodepth=16 \ > --rw=randwrite --bs=4k --direct=1 --size=1G --verify=crc32; > done > > in a PV guest whilst running: > > while true; > do echo vbd-$DOMID-$VBD >unbind; > echo unbound; > sleep 5; > echo vbd-$DOMID-$VBD >bind; > echo bound; > sleep 3; > done > > in dom0 from /sys/bus/xen-backend/drivers/vbd to continuously unbind and > re-bind its system disk image. > > This is a highly useful feature for a backend module as it allows it to be > unloaded and re-loaded (i.e. updated) without requiring domUs to be halted. > This was also tested by running: > > while true; > do echo vbd-$DOMID-$VBD >unbind; > echo unbound; > sleep 5; > rmmod xen-blkback; > echo unloaded; > sleep 1; > modprobe xen-blkback; > echo bound; > cd $(pwd); > sleep 3; > done > > in dom0 whilst running the same loop as above in the (single) PV guest. > > Some (less stressful) testing has also been done using a Windows HVM guest > with the latest 9.0 PV drivers installed. > > Signed-off-by: Paul Durrant Reviewed-by: Roger Pau Monné Thanks! Juergen: I guess you will also pick this series and merge it from the Xen tree instead of the block one? Roger.