Hi OIivier Comments inline. Regards, Hemant > -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Olivier Deme > Sent: 25/Feb/2015 5:44 PM > To: dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH] kni:optimization of rte_kni_rx_burst > > Thank you Hemant, I think there might be one issue left with the patch though. > The alloc_q must initially be filled with mbufs before getting mbuf back on > the > tx_q. > > So the patch should allow rte_kni_rx_burst to check if alloc_q is empty. > If so, it should invoke kni_allocate_mbufs(kni, 0) (to fill the alloc_q with > MAX_MBUF_BURST_NUM mbufs) > > The patch for rte_kni_rx_burst would then look like: > > @@ -575,7 +575,7 @@ rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf > **mbufs, unsigned num) > > /* If buffers removed, allocate mbufs and then put them into alloc_q */ > if (ret) > - kni_allocate_mbufs(kni); > + kni_allocate_mbufs(kni, ret); > + else if (unlikely(kni->alloc_q->write == kni->alloc_q->read)) > + kni_allocate_mbufs(kni, 0); > [hemant] This will introduce a run-time check.
I missed to include the other change in the patch. I am doing it in kni_alloc i.e. initiate the alloc_q with default burst size. kni_allocate_mbufs(ctx, 0); In a way, we are now suggesting to reduce the size of alloc_q to only default burst size. Can we reach is situation, when the kernel is adding packets faster in tx_q than the application is able to dequeue? alloc_q can be empty in this case and kernel will be striving. > > Olivier. > > On 25/02/15 11:48, Hemant Agrawal wrote: > > From: Hemant Agrawal <hemant at freescale.com> > > > > if any buffer is read from the tx_q, MAX_BURST buffers will be allocated and > attempted to be added to to the alloc_q. > > This seems terribly inefficient and it also looks like the alloc_q will > > quickly fill > to its maximum capacity. If the system buffers are low in number, it will > reach > "out of memory" situation. > > > > This patch allocates the number of buffers as many dequeued from tx_q. > > > > Signed-off-by: Hemant Agrawal <hemant at freescale.com> > > --- > > lib/librte_kni/rte_kni.c | 13 ++++++++----- > > 1 file changed, 8 insertions(+), 5 deletions(-) > > > > diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c index > > 4e70fa0..4cf8e30 100644 > > --- a/lib/librte_kni/rte_kni.c > > +++ b/lib/librte_kni/rte_kni.c > > @@ -128,7 +128,7 @@ struct rte_kni_memzone_pool { > > > > > > static void kni_free_mbufs(struct rte_kni *kni); -static void > > kni_allocate_mbufs(struct rte_kni *kni); > > +static void kni_allocate_mbufs(struct rte_kni *kni, int num); > > > > static volatile int kni_fd = -1; > > static struct rte_kni_memzone_pool kni_memzone_pool = { @@ -575,7 > > +575,7 @@ rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf > > **mbufs, unsigned num) > > > > /* If buffers removed, allocate mbufs and then put them into alloc_q > */ > > if (ret) > > - kni_allocate_mbufs(kni); > > + kni_allocate_mbufs(kni, ret); > > > > return ret; > > } > > @@ -594,7 +594,7 @@ kni_free_mbufs(struct rte_kni *kni) > > } > > > > static void > > -kni_allocate_mbufs(struct rte_kni *kni) > > +kni_allocate_mbufs(struct rte_kni *kni, int num) > > { > > int i, ret; > > struct rte_mbuf *pkts[MAX_MBUF_BURST_NUM]; @@ -620,7 +620,10 > @@ > > kni_allocate_mbufs(struct rte_kni *kni) > > return; > > } > > > > - for (i = 0; i < MAX_MBUF_BURST_NUM; i++) { > > + if (num == 0 || num > MAX_MBUF_BURST_NUM) > > + num = MAX_MBUF_BURST_NUM; > > + > > + for (i = 0; i < num; i++) { > > pkts[i] = rte_pktmbuf_alloc(kni->pktmbuf_pool); > > if (unlikely(pkts[i] == NULL)) { > > /* Out of memory */ > > @@ -636,7 +639,7 @@ kni_allocate_mbufs(struct rte_kni *kni) > > ret = kni_fifo_put(kni->alloc_q, (void **)pkts, i); > > > > /* Check if any mbufs not put into alloc_q, and then free them */ > > - if (ret >= 0 && ret < i && ret < MAX_MBUF_BURST_NUM) > {MAX_MBUF_BURST_NUM > > > > + if (ret >= 0 && ret < i && ret < num) { > > int j; > > > > for (j = ret; j < i; j++) > > -- > *Olivier Dem?* > *Druid Software Ltd.* > *Tel: +353 1 202 1831* > *Email: odeme at druidsoftware.com <mailto:odeme at druidsoftware.com>* > *URL: http://www.druidsoftware.com* > *Hall 7, stand 7F70.* > Druid Software: Monetising enterprise small cells solutions.