[dpdk-dev] [PATCH v2 04/24] virtio: Add support for Link State interrupt

Ouyang, Changchun changchun.ouyang at intel.com
Wed Jan 28 04:03:32 CET 2015


Hi Stephen,

> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> Sent: Tuesday, January 27, 2015 6:00 PM
> To: Xie, Huawei
> Cc: Ouyang, Changchun; dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v2 04/24] virtio: Add support for Link State
> interrupt
> 
> On Tue, 27 Jan 2015 09:04:07 +0000
> "Xie, Huawei" <huawei.xie at intel.com> wrote:
> 
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ouyang
> > > Changchun
> > > Sent: Tuesday, January 27, 2015 10:36 AM
> > > To: dev at dpdk.org
> > > Subject: [dpdk-dev] [PATCH v2 04/24] virtio: Add support for Link
> > > State interrupt
> > >
> > > Virtio has link state interrupt which can be used.
> > >
> > > Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> > > Signed-off-by: Changchun Ouyang <changchun.ouyang at intel.com>
> > > ---
> > >  lib/librte_pmd_virtio/virtio_ethdev.c | 78
> > > +++++++++++++++++++++++++++------
> > > --
> > >  lib/librte_pmd_virtio/virtio_pci.c    | 22 ++++++++++
> > >  lib/librte_pmd_virtio/virtio_pci.h    |  4 ++
> > >  3 files changed, 86 insertions(+), 18 deletions(-)
> > >
> > > diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c
> > > b/lib/librte_pmd_virtio/virtio_ethdev.c
> > > index 5df3b54..ef87ff8 100644
> > > --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> > > +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> > > @@ -845,6 +845,34 @@ static int virtio_resource_init(struct
> > > rte_pci_device *pci_dev __rte_unused)  #endif
> > >
> > >  /*
> > > + * Process Virtio Config changed interrupt and call the callback
> > > + * if link state changed.
> > > + */
> > > +static void
> > > +virtio_interrupt_handler(__rte_unused struct rte_intr_handle *handle,
> > > +			 void *param)
> > > +{
> > > +	struct rte_eth_dev *dev = param;
> > > +	struct virtio_hw *hw =
> > > +		VIRTIO_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> > > +	uint8_t isr;
> > > +
> > > +	/* Read interrupt status which clears interrupt */
> > > +	isr = vtpci_isr(hw);
> > > +	PMD_DRV_LOG(INFO, "interrupt status = %#x", isr);
> > > +
> > > +	if (rte_intr_enable(&dev->pci_dev->intr_handle) < 0)
> > > +		PMD_DRV_LOG(ERR, "interrupt enable failed");
> > > +
> >
> > Is it better to put rte_intr_enable after we have handled the interrupt.
> > Is there the possibility of interrupt reentrant in uio intr framework?
> 
> The UIO framework handles IRQ's via posix thread that is reading fd, then
> calling this code. Therefore it is always single threaded.

Even if it is under UIO framework, and always single threaded, 
How about move rte_intr_enable after the virtio_dev_link_update() and _rte_eth_dev_callback_process is called.
This make it more like interrupt handler in linux kernel.
What do you think of it?
Thanks
Changchun



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