Hi, Steve,
Best Regards,
Mark
> -----Original Message-----
> From: Liang, Cunming
> Sent: Thursday, October 29, 2015 4:15 PM
> To: Chen, Jing D; dev at dpdk.org
> Cc: Tao, Zhe; He, Shaopeng; Ananyev, Konstantin; Richardson, Bruce
> Subject: RE: [PATCH v3 04/16] fm10k: add func to re-allocate mbuf for RX ring
>
> Hi Mark?
>
>
> > -----Original Message-----
> > From: Chen, Jing D
> > Sent: Thursday, October 29, 2015 1:24 PM
> > To: Liang, Cunming; dev at dpdk.org
> > Cc: Tao, Zhe; He, Shaopeng; Ananyev, Konstantin; Richardson, Bruce
> > Subject: RE: [PATCH v3 04/16] fm10k: add func to re-allocate mbuf for RX
> ring
> >
> > Hi, Steve,
> >
> > Best Regards,
> > Mark
> >
> >
> > > -----Original Message-----
> > > From: Liang, Cunming
> > > Sent: Wednesday, October 28, 2015 9:59 PM
> > > To: Chen, Jing D; dev at dpdk.org
> > > Cc: Tao, Zhe; He, Shaopeng; Ananyev, Konstantin; Richardson, Bruce
> > > Subject: Re: [PATCH v3 04/16] fm10k: add func to re-allocate mbuf for RX
> ring
> > >
> > > Hi Mark,
> > >
> > > On 10/27/2015 5:46 PM, Chen Jing D(Mark) wrote:
> > > > From: "Chen Jing D(Mark)" <jing.d.chen at intel.com>
> > > >
> > > > Add function fm10k_rxq_rearm to re-allocate mbuf for used desc
> > > > in RX HW ring.
> > > >
> > > > Signed-off-by: Chen Jing D(Mark) <jing.d.chen at intel.com>
> > > > ---
> > > > drivers/net/fm10k/fm10k.h | 9 ++++
> > > > drivers/net/fm10k/fm10k_ethdev.c | 3 +
> > > > drivers/net/fm10k/fm10k_rxtx_vec.c | 90
> > > ++++++++++++++++++++++++++++++++++++
> > > > 3 files changed, 102 insertions(+), 0 deletions(-)
> > > [...]
> > > > +static inline void
> > > > +fm10k_rxq_rearm(struct fm10k_rx_queue *rxq)
> > > > +{
> > > > + int i;
> > > > + uint16_t rx_id;
> > > > + volatile union fm10k_rx_desc *rxdp;
> > > > + struct rte_mbuf **mb_alloc = &rxq->sw_ring[rxq->rxrearm_start];
> > > > + struct rte_mbuf *mb0, *mb1;
> > > > + __m128i head_off = _mm_set_epi64x(
> > > > + RTE_PKTMBUF_HEADROOM +
> > > FM10K_RX_DATABUF_ALIGN - 1,
> > > > + RTE_PKTMBUF_HEADROOM +
> > > FM10K_RX_DATABUF_ALIGN - 1);
> > > > + __m128i dma_addr0, dma_addr1;
> > > > + /* Rx buffer need to be aligned with 512 byte */
> > > > + const __m128i hba_msk = _mm_set_epi64x(0,
> > > > + UINT64_MAX - FM10K_RX_DATABUF_ALIGN
> > > + 1);
> > > > +
> > > > + rxdp = rxq->hw_ring + rxq->rxrearm_start;
> > > > +
> > > > + /* Pull 'n' more MBUFs into the software ring */
> > > > + if (rte_mempool_get_bulk(rxq->mp,
> > > > + (void *)mb_alloc,
> > > > + RTE_FM10K_RXQ_REARM_THRESH) < 0) {
> > > Here's one potential issue when the failure happens. As tail won't
> > > update, the head will equal to tail in the end. HW won't write back
> > > anyway, however the SW recv_raw_pkts_vec only check DD bit, the old
> > > 'dirty' descriptor(DD bit is not clean) will be taken and continue move
> > > forward to check the next which even beyond the tail. I'm sorry didn't
> > > catch it on the first time. /Steve
> >
> > I have a different view on this. In case mbuf allocation always failed and
> > tail
> > equaled to head,
> > then HW will stop to send new packet to HW ring, as you pointed out. Then,
> > when
> > Mbuf can be allocated, this function will refill HW ring and update tail.
> We can't guarantee it successful to recover and allocates new mbuf before
> the polling SW already move beyond the un-rearmed dirty entry.
> So, HW
Thanks! I got you. I'll change accordingly.
> > will
> > resume to fill packet to HW ring. Receive functions will continue to work.
> The point is HW is pending on that moment, but polling receive function
> won't wait, it just read next DD, but the value is 1 which hasn't cleared.
> > Anything I missed?
> >
> > > > + rte_eth_devices[rxq->port_id].data->rx_mbuf_alloc_failed
> > > +=
> > > > + RTE_FM10K_RXQ_REARM_THRESH;
> > > > + return;
> > > > + }
> > > > +
> > > > +
