From: "Hemant@freescale.com" <Hemant@freescale.com>
To: Olivier Deme <odeme@druidsoftware.com>, "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] kni:optimization of rte_kni_rx_burst
Date: Wed, 25 Feb 2015 12:24:34 +0000 [thread overview]
Message-ID: <BY2PR0301MB069369AA0C7436E5F9A63AE9C2170@BY2PR0301MB0693.namprd03.prod.outlook.com> (raw)
In-Reply-To: <54EDBC76.2050507@druidsoftware.com>
Hi OIivier
Comments inline.
Regards,
Hemant
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Deme
> Sent: 25/Feb/2015 5:44 PM
> To: dev@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@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@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 Demé*
> *Druid Software Ltd.*
> *Tel: +353 1 202 1831*
> *Email: odeme@druidsoftware.com <mailto:odeme@druidsoftware.com>*
> *URL: http://www.druidsoftware.com*
> *Hall 7, stand 7F70.*
> Druid Software: Monetising enterprise small cells solutions.
next prev parent reply other threads:[~2015-02-25 12:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-25 11:48 Hemant Agrawal
2015-02-25 12:13 ` Olivier Deme
2015-02-25 12:24 ` Hemant [this message]
2015-02-25 12:28 ` Olivier Deme
2015-02-25 12:38 ` Marc Sune
2015-02-25 12:51 ` Olivier Deme
2015-02-25 13:29 ` Jay Rolette
2015-02-26 7:00 ` Hemant
2015-02-26 12:56 ` Marc Sune
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