Hi Bruce, <snip>
> Subject: Re: [dpdk-dev] [PATCH v3 3/4] bonding: take queue spinlock in rx/tx > burst functions > > On Sun, Jun 12, 2016 at 06:11:28PM +0100, Bernard Iremonger wrote: > > Use rte_spinlock_trylock() in the rx/tx burst functions to take the > > queue spinlock. > > > > Signed-off-by: Bernard Iremonger <bernard.iremonger at intel.com> > > Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com> > > --- > > Why does this particular PMD need spinlocks when doing RX and TX, while > other device types do not? How is adding/removing devices from a bonded > device different to other control operations that can be done on physical > PMDs? Is this not similar to say bringing down or hotplugging out a physical > port just before an RX or TX operation takes place? > For all other PMDs we rely on the app to synchronise control and data plane > operation - why not here? > > /Bruce This issue arose during VM live migration testing. For VM live migration it is necessary (while traffic is running) to be able to remove a bonded slave device, stop it, close it and detach it. It a slave device is removed from a bonded device while traffic is running a segmentation fault may occur in the rx/tx burst function. The spinlock has been added to prevent this occurring. The bonding device already uses a spinlock to synchronise between the add and remove functionality and the slave_link_status_change_monitor code. Previously testpmd did not allow, stop, close or detach of PMD while traffic was running. Testpmd has been modified with the following patchset http://dpdk.org/dev/patchwork/patch/13472/ It now allows stop, close and detach of a PMD provided in it is not forwarding and is not a slave of bonded PMD. Regards, Bernard.
