From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: "dev@dpdk.org" <dev@dpdk.org>, Hanoh Haim <hhaim@cisco.com>
Subject: Re: [dpdk-dev] [PATCH] mbuf: cleanup rte_pktmbuf_lastseg(), fix atomic usage
Date: Wed, 15 Nov 2017 11:08:17 +0000 [thread overview]
Message-ID: <2601191342CEEE43887BDE71AB9772585FABD3F5@irsmsx105.ger.corp.intel.com> (raw)
Hi Hanon,
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Hanoh Haim
> Sent: Wednesday, November 15, 2017 8:36 AM
> To: dev@dpdk.org
> Cc: Hanoh Haim <hhaim@cisco.com>
> Subject: [dpdk-dev] [PATCH] mbuf: cleanup rte_pktmbuf_lastseg(), fix atomic usage
>
> Signed-off-by: Hanoh Haim <hhaim@cisco.com>
> ---
> lib/librte_mbuf/rte_mbuf.h | 27 +++++++++++++--------------
> 1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 7e326bb..ab110f8 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -1159,6 +1159,15 @@ static inline void rte_pktmbuf_reset(struct rte_mbuf *m)
> __rte_mbuf_sanity_check(m, 1);
> }
>
> +
> +static __rte_always_inline void rte_pktmbuf_reset_before_free(struct rte_mbuf *m)
> +{
> + if (m->next != NULL) {
> + m->next = NULL;
> + m->nb_segs = 1;
> + }
> +}
> +
> /**
> * Allocate a new mbuf from a mempool.
> *
> @@ -1323,8 +1332,7 @@ static inline void rte_pktmbuf_detach(struct rte_mbuf *m)
> m->ol_flags = 0;
>
> if (rte_mbuf_refcnt_update(md, -1) == 0) {
> - md->next = NULL;
> - md->nb_segs = 1;
> + rte_pktmbuf_reset_before_free(md);
> rte_mbuf_refcnt_set(md, 1);
> rte_mbuf_raw_free(md);
> }
> @@ -1354,25 +1362,16 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
> if (RTE_MBUF_INDIRECT(m))
> rte_pktmbuf_detach(m);
>
> - if (m->next != NULL) {
> - m->next = NULL;
> - m->nb_segs = 1;
> - }
> -
> + rte_pktmbuf_reset_before_free(m);
> return m;
>
> - } else if (rte_atomic16_add_return(&m->refcnt_atomic, -1) == 0) {
> -
> + } else if (rte_mbuf_refcnt_update(m, -1) == 0) {
That would cause extra read; cmp (and possible slowdown) for atomic refcnt.
If that really need to be fixed - probably we need to introduce a new function
that would do update without trying to read refctn first - rte_mbuf_refcnt_update_blind() or so.
Konstantin
>
> if (RTE_MBUF_INDIRECT(m))
> rte_pktmbuf_detach(m);
>
> - if (m->next != NULL) {
> - m->next = NULL;
> - m->nb_segs = 1;
> - }
> + rte_pktmbuf_reset_before_free(m);
> rte_mbuf_refcnt_set(m, 1);
> -
> return m;
> }
> return NULL;
> --
> 2.9.3
next reply other threads:[~2017-11-15 11:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-15 11:08 Ananyev, Konstantin [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-11-15 8:35 Hanoh Haim
2017-11-15 8:50 ` Ananyev, Konstantin
2017-11-15 8:30 Hanoh Haim
2017-11-15 8:41 ` Olivier MATZ
2017-11-15 8:25 Hanoh Haim
2017-11-15 8:16 Hanoh Haim
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