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

[Jens Freimann <jfreimann@redhat.com>]

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

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

regards,
Jens