Re: [dpdk-dev] [PATCH v2 1/3] net/virtio: inline refill and offload helpers

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 12/19/18 11:53 AM, Jens Freimann wrote:
> On Wed, Dec 19, 2018 at 10:26:10AM +0000, Gavin Hu (Arm Technology 
> China) wrote:
>>
>>
>>> -----Original Message-----
>>> From: dev <dev-bounces@dpdk.org> On Behalf Of Jens Freimann
>>> Sent: Wednesday, December 19, 2018 5:25 PM
>>> To: Maxime Coquelin <maxime.coquelin@redhat.com>
>>> Cc: dev@dpdk.org; tiwei.bie@intel.com; zhihong.wang@intel.com
>>> Subject: Re: [dpdk-dev] [PATCH v2 1/3] net/virtio: inline refill and 
>>> offload
>>> helpers
>>>
>>> On Tue, Dec 11, 2018 at 02:48:02PM +0100, Maxime Coquelin wrote:
>>> >Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>> >---
>>> > drivers/net/virtio/virtio_rxtx.c | 8 ++++----
>>> > 1 file changed, 4 insertions(+), 4 deletions(-)
>>> >
>>> >diff --git a/drivers/net/virtio/virtio_rxtx.c
>>> >b/drivers/net/virtio/virtio_rxtx.c
>>> >index eb891433e..e1c270b1c 100644
>>> >--- a/drivers/net/virtio/virtio_rxtx.c
>>> >+++ b/drivers/net/virtio/virtio_rxtx.c
>>> >@@ -741,7 +741,7 @@ virtio_dev_tx_queue_setup_finish(struct
>>> rte_eth_dev *dev,
>>> >     return 0;
>>> > }
>>> >
>>> >-static void
>>> >+static inline void
>>> > virtio_discard_rxbuf(struct virtqueue *vq, struct rte_mbuf *m)  {
>>> >     int error;
>>> >@@ -757,7 +757,7 @@ virtio_discard_rxbuf(struct virtqueue *vq, struct
>>> rte_mbuf *m)
>>> >     }
>>> > }
>>> >
>>> >-static void
>>> >+static inline void
>>> > virtio_discard_rxbuf_inorder(struct virtqueue *vq, struct rte_mbuf *m)
>>> >{
>>> >     int error;
>>> >@@ -769,7 +769,7 @@ virtio_discard_rxbuf_inorder(struct virtqueue *vq,
>>> struct rte_mbuf *m)
>>> >     }
>>> > }
>>> >
>>> >-static void
>>> >+static inline void
>>> > virtio_update_packet_stats(struct virtnet_stats *stats, struct
>>> >rte_mbuf *mbuf)  {
>>> >     uint32_t s = mbuf->pkt_len;
>>> >@@ -811,7 +811,7 @@ virtio_rx_stats_updated(struct virtnet_rx *rxvq,
>>> >struct rte_mbuf *m)  }
>>> >
>>> > /* Optionally fill offload information in structure */ -static int
>>> >+static inline int
>>> > virtio_rx_offload(struct rte_mbuf *m, struct virtio_net_hdr *hdr) {
>>> >     struct rte_net_hdr_lens hdr_lens;
>>>
>>> since these are all static functions, does declaring them inline 
>>> actually help
>>> or are they inlined anyway by the compiler?
>>>
>>> regards,
>>> Jens
>>
>> By disassembling the code, static function calls translate to "bl 
>> XXX", that means they are not inline.
>> Inline is not always working, maybe __rte_always_inline is required here?
> 
> I think always_inline is only to force inline when no optimiziation is
> done? https://gcc.gnu.org/onlinedocs/gcc/Inline.html
> 
> I don't know if there's a way to really force the compiler to inline
> it or if it's better anyway to trust the compiler. It doesn't hurt to 
> have the functions declared inline except that it
> clutters code a bit, but I don't have strong feelings against leaving this
> patch as is.  Leaving it to Maxime, so

I need to consider the use of __rte_always_inline generally in
virtio_rxtx.c.

In this specific case, inline seems enough.

> 
> Reviewed-by: Jens Freimann <jfreimann@redhat.com>

Thanks,
Maxime

> regards,
> Jens