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From: Feifei Wang <Feifei.Wang2@arm.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	"Yigit, Ferruh" <ferruh.yigit@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, nd <nd@arm.com>,
	"stable@dpdk.org" <stable@dpdk.org>,
	Ruifeng Wang <Ruifeng.Wang@arm.com>, nd <nd@arm.com>
Subject: [dpdk-stable] 回复: [RFC PATCH v2 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration
Date: Sun, 26 Sep 2021 02:19:27 +0000
Message-ID: <DB9PR08MB69232117B8ED548B6F6D955FC8A69@DB9PR08MB6923.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <DM6PR11MB4491BDB787745D60AB489EF69AA49@DM6PR11MB4491.namprd11.prod.outlook.com>


> -----邮件原件-----
> 发件人: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> 发送时间: Saturday, September 25, 2021 2:08 AM
> 收件人: Feifei Wang <Feifei.Wang2@arm.com>; Yigit, Ferruh
> <ferruh.yigit@intel.com>
> 抄送: dev@dpdk.org; nd <nd@arm.com>; stable@dpdk.org; Ruifeng Wang
> <Ruifeng.Wang@arm.com>
> 主题: RE: [RFC PATCH v2 4/5] lib/bpf: use wait event scheme for Rx/Tx
> iteration
> 
> 
> >
> > First, fix the bug that keyword const of func arg should be after "*".
> 
> I believe there is no bug here.
> 
> > This is because const before "*" means the value of "cbi" should not
> > be changed.
> 
> Exactly, it says that the function itself will not change the value of "cbi".
> It just waits for the value to be changed by someone else.
> So please keep parameter list intact.

Thanks for your explanation. The reason I changed is that I ever used rte_wait_until_xx(validate *addr) API here,
And there is conflict between "const" and "validate", complier will report warning here.
But now I think since I keep it as it is, there will be no warning due to new macro has no "validate".
I will delete this unnecessary bug fix.
> 
> > But we should monitor that cbi->use changed and then we can jump out
> > of loop.
> >
> > Second, instead of polling for cbi->use to be updated, use wait event
> > scheme.
> >
> > Fixes: a93ff62a8938 ("bpf: introduce basic Rx/Tx filters")
> > Cc: konstantin.ananyev@intel.com
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > ---
> >  lib/bpf/bpf_pkt.c | 11 ++++-------
> >  1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/lib/bpf/bpf_pkt.c b/lib/bpf/bpf_pkt.c index
> > 6e8248f0d6..08ed8ff68c 100644
> > --- a/lib/bpf/bpf_pkt.c
> > +++ b/lib/bpf/bpf_pkt.c
> > @@ -111,9 +111,9 @@ bpf_eth_cbi_unuse(struct bpf_eth_cbi *cbi)
> >   * Waits till datapath finished using given callback.
> >   */
> >  static void
> > -bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
> > +bpf_eth_cbi_wait(struct bpf_eth_cbi *const cbi)
> >  {
> > -	uint32_t nuse, puse;
> > +	uint32_t puse;
> >
> >  	/* make sure all previous loads and stores are completed */
> >  	rte_smp_mb();
> > @@ -122,11 +122,8 @@ bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
> >
> >  	/* in use, busy wait till current RX/TX iteration is finished */
> >  	if ((puse & BPF_ETH_CBI_INUSE) != 0) {
> > -		do {
> > -			rte_pause();
> > -			rte_compiler_barrier();
> > -			nuse = cbi->use;
> > -		} while (nuse == puse);
> > +		rte_compiler_barrier();
> > +		rte_wait_event_32(&cbi->use, UINT_MAX, puse, ==,
> __ATOMIC_RELAXED);
> >  	}
> >  }
> >
> > --
> > 2.25.1


      reply	other threads:[~2021-09-26  2:20 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210902053253.3017858-1-feifei.wang2@arm.com>
2021-09-02  5:32 ` [dpdk-stable] [RFC PATCH v1 4/5] lib/bpf: use wait until " Feifei Wang
     [not found] ` <20210923095902.301762-1-feifei.wang2@arm.com>
2021-09-23  9:59   ` [dpdk-stable] [RFC PATCH v2 4/5] lib/bpf: use wait event " Feifei Wang
2021-09-24 18:07     ` Ananyev, Konstantin
2021-09-26  2:19       ` Feifei Wang [this message]

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