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From: Stephen Hemminger <stephen@networkplumber.org>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API
Date: Fri, 18 Dec 2015 09:32:06 -0800	[thread overview]
Message-ID: <20151218093206.35e2e3e4@xeon-e3> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB97725836AD5AEB@irsmsx105.ger.corp.intel.com>

On Fri, 18 Dec 2015 10:44:02 +0000
"Ananyev, Konstantin" <konstantin.ananyev@intel.com> wrote:

> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen Hemminger
> > Sent: Friday, December 18, 2015 5:01 AM
> > To: Xie, Huawei
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API
> > 
> > On Mon, 14 Dec 2015 09:14:41 +0800
> > Huawei Xie <huawei.xie@intel.com> wrote:
> > 
> > > v2 changes:
> > >  unroll the loop a bit to help the performance
> > >
> > > rte_pktmbuf_alloc_bulk allocates a bulk of packet mbufs.
> > >
> > > There is related thread about this bulk API.
> > > http://dpdk.org/dev/patchwork/patch/4718/
> > > Thanks to Konstantin's loop unrolling.
> > >
> > > Signed-off-by: Gerald Rogers <gerald.rogers@intel.com>
> > > Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> > > Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> > > ---
> > >  lib/librte_mbuf/rte_mbuf.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 50 insertions(+)
> > >
> > > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> > > index f234ac9..4e209e0 100644
> > > --- a/lib/librte_mbuf/rte_mbuf.h
> > > +++ b/lib/librte_mbuf/rte_mbuf.h
> > > @@ -1336,6 +1336,56 @@ static inline struct rte_mbuf *rte_pktmbuf_alloc(struct rte_mempool *mp)
> > >  }
> > >
> > >  /**
> > > + * Allocate a bulk of mbufs, initialize refcnt and reset the fields to default
> > > + * values.
> > > + *
> > > + *  @param pool
> > > + *    The mempool from which mbufs are allocated.
> > > + *  @param mbufs
> > > + *    Array of pointers to mbufs
> > > + *  @param count
> > > + *    Array size
> > > + *  @return
> > > + *   - 0: Success
> > > + */
> > > +static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool,
> > > +	 struct rte_mbuf **mbufs, unsigned count)
> > > +{
> > > +	unsigned idx = 0;
> > > +	int rc;
> > > +
> > > +	rc = rte_mempool_get_bulk(pool, (void **)mbufs, count);
> > > +	if (unlikely(rc))
> > > +		return rc;
> > > +
> > > +	switch (count % 4) {
> > > +	while (idx != count) {
> > > +		case 0:
> > > +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> > > +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> > > +			rte_pktmbuf_reset(mbufs[idx]);
> > > +			idx++;
> > > +		case 3:
> > > +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> > > +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> > > +			rte_pktmbuf_reset(mbufs[idx]);
> > > +			idx++;
> > > +		case 2:
> > > +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> > > +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> > > +			rte_pktmbuf_reset(mbufs[idx]);
> > > +			idx++;
> > > +		case 1:
> > > +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> > > +			rte_mbuf_refcnt_set(mbufs[idx], 1);
> > > +			rte_pktmbuf_reset(mbufs[idx]);
> > > +			idx++;
> > > +	}
> > > +	}
> > > +	return 0;
> > > +}
> > 
> > This is weird. Why not just use Duff's device in a more normal manner.
> 
> But it is a sort of Duff's method.
> Not sure what looks weird to you here?
> while () {} instead of do {} while();?
> Konstantin
> 
> 
> 

It is unusual to have cases not associated with block of the switch.
Unusual to me means, "not used commonly in most code".

Since you are jumping into the loop, might make more sense as a do { } while()

  reply	other threads:[~2015-12-18 17:31 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-13 23:35 [dpdk-dev] [PATCH 0/2] provide rte_pktmbuf_alloc_bulk API and call it in vhost dequeue Huawei Xie
2015-12-13 23:35 ` [dpdk-dev] [PATCH 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2015-12-13 23:35 ` [dpdk-dev] [PATCH 2/2] vhost: call rte_pktmbuf_alloc_bulk in vhost dequeue Huawei Xie
2015-12-14  1:14 ` [dpdk-dev] [PATCH v2 0/2] provide rte_pktmbuf_alloc_bulk API and call it " Huawei Xie
2015-12-14  1:14   ` [dpdk-dev] [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2015-12-17  6:41     ` Yuanhan Liu
2015-12-17 15:42       ` Ananyev, Konstantin
2015-12-18  2:17         ` Yuanhan Liu
2015-12-18  5:01     ` Stephen Hemminger
2015-12-18  5:21       ` Yuanhan Liu
2015-12-18  7:10       ` Xie, Huawei
2015-12-18 10:44       ` Ananyev, Konstantin
2015-12-18 17:32         ` Stephen Hemminger [this message]
2015-12-18 19:27           ` Wiles, Keith
2015-12-21 15:21             ` Xie, Huawei
2015-12-21 17:20               ` Wiles, Keith
2015-12-21 21:30                 ` Thomas Monjalon
2015-12-22  1:58                   ` Xie, Huawei
2015-12-21 22:34               ` Don Provan
2015-12-21 12:25           ` Xie, Huawei
2015-12-14  1:14   ` [dpdk-dev] [PATCH v2 2/2] vhost: call rte_pktmbuf_alloc_bulk in vhost dequeue Huawei Xie
2015-12-17  6:41     ` Yuanhan Liu
2015-12-22 16:17   ` [dpdk-dev] [PATCH v3 0/2] provide rte_pktmbuf_alloc_bulk API and call it " Huawei Xie
2015-12-22 16:17     ` [dpdk-dev] [PATCH v3 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2015-12-23 18:37       ` Stephen Hemminger
2015-12-23 18:49         ` Ananyev, Konstantin
2015-12-24  1:33           ` Xie, Huawei
2015-12-22 16:17     ` [dpdk-dev] [PATCH v3 2/2] vhost: call rte_pktmbuf_alloc_bulk in vhost dequeue Huawei Xie
2015-12-23 11:22       ` linhaifeng
2015-12-23 11:39         ` Xie, Huawei
2015-12-22 23:05 ` [dpdk-dev] [PATCH v4 0/2] provide rte_pktmbuf_alloc_bulk API and call it " Huawei Xie
2015-12-22 23:05   ` [dpdk-dev] [PATCH v4 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2015-12-22 23:05   ` [dpdk-dev] [PATCH v4 2/2] vhost: call rte_pktmbuf_alloc_bulk in vhost dequeue Huawei Xie
2015-12-27 16:38 ` [dpdk-dev] [PATCH v5 0/2] provide rte_pktmbuf_alloc_bulk API and call it " Huawei Xie
2015-12-27 16:38   ` [dpdk-dev] [PATCH v5 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2015-12-27 16:38   ` [dpdk-dev] [PATCH v5 2/2] vhost: call rte_pktmbuf_alloc_bulk in vhost dequeue Huawei Xie
2016-01-26 17:03 ` [dpdk-dev] [PATCH v6 0/2] provide rte_pktmbuf_alloc_bulk API and call it " Huawei Xie
2016-01-26 17:03   ` [dpdk-dev] [PATCH v6 1/2] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2016-01-27 13:56     ` Panu Matilainen
2016-02-03 17:23       ` Olivier MATZ
2016-02-22 14:49         ` Xie, Huawei
2016-02-23  5:35           ` Xie, Huawei
2016-02-24 12:11             ` Panu Matilainen
2016-02-24 13:23               ` Ananyev, Konstantin
2016-02-26  7:39                 ` Xie, Huawei
2016-02-26  8:45                   ` Olivier MATZ
2016-02-29 10:51                 ` Panu Matilainen
2016-02-29 16:14                   ` Thomas Monjalon
2016-02-26  8:55             ` Olivier MATZ
2016-02-26  9:07               ` Xie, Huawei
2016-02-26  9:18                 ` Olivier MATZ
2016-01-26 17:03   ` [dpdk-dev] [PATCH v6 2/2] vhost: call rte_pktmbuf_alloc_bulk in vhost dequeue Huawei Xie
2016-02-28 12:44 ` [dpdk-dev] [PATCH v7] mbuf: provide rte_pktmbuf_alloc_bulk API Huawei Xie
2016-02-29 16:27   ` Thomas Monjalon

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