From: Bruce Richardson <bruce.richardson@intel.com>
To: "Mattias Rönnblom" <mattias.ronnblom@ericsson.com>
Cc: "Morten Brørup" <mb@smartsharesystems.com>,
olivier.matz@6wind.com, stephen@networkplumber.org,
harry.van.haaren@intel.com, konstantin.ananyev@intel.com,
dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2 2/2] mbuf: add bulk free function
Date: Thu, 26 Sep 2019 09:30:25 +0100 [thread overview]
Message-ID: <20190926083024.GA1821@bricha3-MOBL.ger.corp.intel.com> (raw)
In-Reply-To: <b0633c2e-6e8e-dce7-ca2e-7cde0a6e0e74@ericsson.com>
On Wed, Sep 25, 2019 at 09:02:28PM +0200, Mattias Rönnblom wrote:
> On 2019-09-25 14:03, Morten Brørup wrote:
> > Add function for freeing a bulk of mbufs.
> >
> > Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> > ---
> > lib/librte_mbuf/rte_mbuf.c | 35 +++++++++++++++++++++++++++++++++++
> > lib/librte_mbuf/rte_mbuf.h | 16 +++++-----------
> > 2 files changed, 40 insertions(+), 11 deletions(-)
> >
> > diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
> > index 37718d49c..b63a0eced 100644
> > --- a/lib/librte_mbuf/rte_mbuf.c
> > +++ b/lib/librte_mbuf/rte_mbuf.c
> > @@ -245,6 +245,41 @@ int rte_mbuf_check(const struct rte_mbuf *m, int is_header,
> > return 0;
> > }
> > +/**
> > + * Maximum bulk of mbufs rte_pktmbuf_free_bulk() returns to mempool.
> > + */
> > +#define RTE_PKTMBUF_FREE_BULK_SZ 64
> > +
> > +/* Free a bulk of mbufs back into their original mempools. */
> > +void rte_pktmbuf_free_bulk(struct rte_mbuf **mbufs, unsigned int count)
> > +{
> > + struct rte_mbuf *m, *free[RTE_PKTMBUF_FREE_BULK_SZ];
> > + unsigned int idx, nb_free = 0;
> > +
> > + for (idx = 0; idx < count; idx++) {
> > + m = mbufs[idx];
> > + if (unlikely(m == NULL))
> > + continue;
> > +
> > + __rte_mbuf_sanity_check(m, 1);
> > + m = rte_pktmbuf_prefree_seg(m);
> > + if (unlikely(m == NULL))
> > + continue;
> > +
> > + if (nb_free >= RTE_PKTMBUF_FREE_BULK_SZ ||
> > + (nb_free > 0 && m->pool != free[0]->pool)) {
>
> Maybe an unlikely() would be in order here?
>
I'd caution against it, since it can penalize the cold branch a lot. If a
branch really is predictable the HW branch predictors generally are good
enough to handle it at runtime. So long as a path is a valid path for a
runtime app, i.e. not something like a fatal error only ever hit once in an
entire run, I'd tend to omit likely()/unlikely() calls unless profiling
shows a real performance difference.
/Bruce
next prev parent reply other threads:[~2019-09-26 8:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 12:03 [dpdk-dev] [PATCH v2 0/2] " Morten Brørup
2019-09-25 12:03 ` [dpdk-dev] [PATCH v2 1/2] " Morten Brørup
2019-09-25 12:03 ` [dpdk-dev] [PATCH v2 2/2] " Morten Brørup
[not found] ` <20190925120542.A51B41BE84@dpdk.org>
2019-09-25 12:17 ` [dpdk-dev] |WARNING| pw59738 " Morten Brørup
2019-09-25 23:37 ` Stephen Hemminger
2019-09-27 6:42 ` Morten Brørup
2019-09-25 19:02 ` [dpdk-dev] " Mattias Rönnblom
2019-09-26 8:30 ` Bruce Richardson [this message]
2019-09-26 20:11 ` Mattias Rönnblom
2019-09-27 9:09 ` Bruce Richardson
2019-09-26 9:26 ` Andrew Rybchenko
2019-09-26 15:35 ` Morten Brørup
2019-09-26 10:23 ` Ananyev, Konstantin
2019-09-27 10:22 ` Morten Brørup
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