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From: Feifei Wang <Feifei.Wang2@arm.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, nd <nd@arm.com>,
	Ruifeng Wang <Ruifeng.Wang@arm.com>, nd <nd@arm.com>,
	nd <nd@arm.com>, nd <nd@arm.com>
Subject: [dpdk-dev] 回复: [PATCH v5 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration
Date: Wed, 27 Oct 2021 07:31:10 +0000
Message-ID: <DB9PR08MB69230A3ABCC322B04383FE51C8859@DB9PR08MB6923.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <DB9PR08MB6923070EAADF3121FE95BD3FC8859@DB9PR08MB6923.eurprd08.prod.outlook.com>



> -----邮件原件-----
> 发件人: Feifei Wang
> 发送时间: Wednesday, October 27, 2021 3:04 PM
> 收件人: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> 抄送: dev@dpdk.org; nd <nd@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>; nd <nd@arm.com>; nd <nd@arm.com>
> 主题: 回复: [PATCH v5 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration
> 
> 
> 
> > -----邮件原件-----
> > 发件人: dev <dev-bounces@dpdk.org> 代表 Ananyev, Konstantin
> > 发送时间: Tuesday, October 26, 2021 8:57 PM
> > 收件人: Feifei Wang <Feifei.Wang2@arm.com>
> > 抄送: dev@dpdk.org; nd <nd@arm.com>; Ruifeng Wang
> > <Ruifeng.Wang@arm.com>; nd <nd@arm.com>
> > 主题: Re: [dpdk-dev] [PATCH v5 4/5] lib/bpf: use wait event scheme for
> > Rx/Tx iteration
> >
> >
> > > Hi Feifei,
> > >
> > > > > Instead of polling for cbi->use to be updated, use wait event scheme.
> > > > >
> > > > > Furthermore, delete 'const' for 'bpf_eth_cbi_wait'. This is
> > > > > because of a compilation error:
> > > > > ----------------------------------------------------------------
> > > > > --
> > > > > -----
> > > > > ../lib/eal/include/rte_common.h:36:13: error: read-only variable
> ‘value’
> > > > > used as ‘asm’ output
> > > > >    36 | #define asm __asm__
> > > > >       |             ^~~~~~~
> > > > >
> > > > > ../lib/eal/arm/include/rte_pause_64.h:66:3: note: in expansion
> > > > > of
> > macro ‘asm’
> > > > >    66 |   asm volatile("ldaxr %w[tmp], [%x[addr]]" \
> > > > >       |   ^~~
> > > > >
> > > > > ../lib/eal/arm/include/rte_pause_64.h:96:3: note: in expansion
> > > > > of macro ‘__LOAD_EXC_32’
> > > > >    96 |   __LOAD_EXC_32((src), dst, memorder)     \
> > > > >       |   ^~~~~~~~~~~~~
> > > > >
> > > > > ../lib/eal/arm/include/rte_pause_64.h:167:4: note: in expansion
> > > > > of macro ‘__LOAD_EXC’
> > > > >   167 |    __LOAD_EXC((addr), value, memorder, size) \
> > > > >       |    ^~~~~~~~~~
> > > > >
> > > > > ../lib/bpf/bpf_pkt.c:125:3: note: in expansion of macro
> ‘rte_wait_event’
> > > > >   125 |   rte_wait_event(&cbi->use, UINT32_MAX, ==, puse,
> > > > > ----------------------------------------------------------------
> > > > > --
> > > > > -----
> > > > >
> > > > > 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..213d44a75a 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 *cbi)
> > > >
> > > > Hi, Konstantin
> > > >
> > > > For this bpf patch, I delete 'const' through this is contrary to
> > > > what we discussed earlier. This is because if  we keep 'constant'
> > > > here and
> > use 'rte_wait_event'
> > > > new macro, compiler will report error. And earlier the arm version
> > > > cannot be compiled due to I forgot enable "wfe" config in the
> > > > meson file,
> > so this issue can not happen before.
> > >
> > >
> > > Honestly, I don't understand why we have to remove perfectly valid
> 'const'
> > qualifier here.
> > > If this macro can't be used with pointers to const (still don't
> > > understand why), then let's just not use this macro here.
> > > Strictly speaking I don't see much benefit here from it.
> > >
> > > >
> > > > >  {
> > > > > -	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_wait_event(&cbi->use, UINT32_MAX, ==, puse,
> > > > > +				__ATOMIC_RELAXED);
> >
> > After another thought, if we do type conversion at macro invocation time:
> >
> > bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi) {
> >   ...
> >   rte_wait_event((uint32_t *)&cbi->use, UINT32_MAX, ==, puse,
> > __ATOMIC_RELAXED);
> >
> > would that help?
> 
> I try to with this and it will report compiler warning:
> ' cast discards ‘const’ qualifier'.
> I think this is due to that in rte_wait_event macro, we use
> typeof(*(addr)) value = 0;
>  and value is defined as "const uint32_t", but it should be able to be updated.
> 

Correct a little.
The explain is for 'asm error' in the commit message.

> Furthermore, this reflects the limitations of the new macro, it cannot be
> applied when 'addr' is type of 'const'. Finally, I think I should give up the
> change for "bpf".
> >
> >
> > > > >  	}
> > > > >  }
> > > > >
> > > > > --
> > > > > 2.25.1


  reply	other threads:[~2021-10-27  7:31 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02  5:32 [dpdk-dev] [RFC PATCH v1 0/5] add new API for wait until scheme Feifei Wang
2021-09-02  5:32 ` [dpdk-dev] [RFC PATCH v1 1/5] eal: " Feifei Wang
2021-09-02  5:32 ` [dpdk-dev] [RFC PATCH v1 2/5] eal: use wait until scheme for read pflock Feifei Wang
2021-09-02  5:32 ` [dpdk-dev] [RFC PATCH v1 3/5] eal: use wait until scheme for mcslock Feifei Wang
2021-09-02  5:32 ` [dpdk-dev] [RFC PATCH v1 4/5] lib/bpf: use wait until scheme for Rx/Tx iteration Feifei Wang
2021-09-02  5:32 ` [dpdk-dev] [RFC PATCH v1 5/5] lib/distributor: use wait until scheme Feifei Wang
2021-09-02 15:22 ` [dpdk-dev] [RFC PATCH v1 0/5] add new API for " Stephen Hemminger
2021-09-03  7:02   ` [dpdk-dev] 回复: " Feifei Wang
2021-09-23  9:58 ` [dpdk-dev] [RFC PATCH v2 0/5] add new definitions for wait scheme Feifei Wang
2021-09-23  9:58   ` [dpdk-dev] [RFC PATCH v2 1/5] eal: " Feifei Wang
2021-09-23  9:58   ` [dpdk-dev] [RFC PATCH v2 2/5] eal: use wait event for read pflock Feifei Wang
2021-09-23  9:59   ` [dpdk-dev] [RFC PATCH v2 3/5] eal: use wait event scheme for mcslock Feifei Wang
2021-09-23  9:59   ` [dpdk-dev] [RFC PATCH v2 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration Feifei Wang
2021-09-24 18:07     ` Ananyev, Konstantin
2021-09-26  2:19       ` [dpdk-dev] 回复: " Feifei Wang
2021-09-23  9:59   ` [dpdk-dev] [RFC PATCH v2 5/5] lib/distributor: use wait event scheme Feifei Wang
2021-09-26  6:32 ` [dpdk-dev] [RFC PATCH v3 0/5] add new definitions for wait scheme Feifei Wang
2021-09-26  6:32   ` [dpdk-dev] [RFC PATCH v3 1/5] eal: " Feifei Wang
2021-10-07 16:18     ` Ananyev, Konstantin
2021-10-12  8:09       ` [dpdk-dev] 回复: " Feifei Wang
2021-10-13 15:03         ` [dpdk-dev] " Ananyev, Konstantin
2021-10-13 17:00           ` Stephen Hemminger
2021-10-14  3:14             ` [dpdk-dev] 回复: " Feifei Wang
2021-10-14  3:08           ` Feifei Wang
2021-09-26  6:32   ` [dpdk-dev] [RFC PATCH v3 2/5] eal: use wait event for read pflock Feifei Wang
2021-09-26  6:33   ` [dpdk-dev] [RFC PATCH v3 3/5] eal: use wait event scheme for mcslock Feifei Wang
2021-09-26  6:33   ` [dpdk-dev] [RFC PATCH v3 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration Feifei Wang
2021-10-07 15:50     ` Ananyev, Konstantin
2021-10-07 17:40       ` Ananyev, Konstantin
2021-10-20  6:20         ` [dpdk-dev] 回复: " Feifei Wang
2021-09-26  6:33   ` [dpdk-dev] [RFC PATCH v3 5/5] lib/distributor: use wait event scheme Feifei Wang
2021-10-20  8:45   ` [dpdk-dev] [PATCH v4 0/5] add new definitions for wait scheme Feifei Wang
2021-10-20  8:45     ` [dpdk-dev] [PATCH v4 1/5] eal: " Feifei Wang
2021-10-21 16:24       ` Ananyev, Konstantin
2021-10-25  9:20         ` [dpdk-dev] 回复: " Feifei Wang
2021-10-25 14:28           ` [dpdk-dev] " Ananyev, Konstantin
2021-10-26  1:08             ` [dpdk-dev] 回复: " Feifei Wang
2021-10-22  0:10       ` [dpdk-dev] " Jerin Jacob
2021-10-25  9:30         ` [dpdk-dev] 回复: " Feifei Wang
2021-10-25  9:43           ` [dpdk-dev] " Jerin Jacob
2021-10-26  1:11             ` [dpdk-dev] 回复: " Feifei Wang
2021-10-20  8:45     ` [dpdk-dev] [PATCH v4 2/5] eal: use wait event for read pflock Feifei Wang
2021-10-20  8:45     ` [dpdk-dev] [PATCH v4 3/5] eal: use wait event scheme for mcslock Feifei Wang
2021-10-20  8:45     ` [dpdk-dev] [PATCH v4 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration Feifei Wang
2021-10-20  8:45     ` [dpdk-dev] [PATCH v4 5/5] lib/distributor: use wait event scheme Feifei Wang
2021-10-26  8:01 ` [dpdk-dev] [PATCH v5 0/5] add new definitions for wait scheme Feifei Wang
2021-10-26  8:02   ` [dpdk-dev] [PATCH v5 1/5] eal: " Feifei Wang
2021-10-26  8:08     ` [dpdk-dev] 回复: " Feifei Wang
2021-10-26  9:46       ` [dpdk-dev] " Ananyev, Konstantin
2021-10-26  9:59         ` Ananyev, Konstantin
2021-10-27  6:56           ` [dpdk-dev] 回复: " Feifei Wang
2021-10-26  8:02   ` [dpdk-dev] [PATCH v5 2/5] eal: use wait event for read pflock Feifei Wang
2021-10-26  8:02   ` [dpdk-dev] [PATCH v5 3/5] eal: use wait event scheme for mcslock Feifei Wang
2021-10-26  8:02   ` [dpdk-dev] [PATCH v5 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration Feifei Wang
2021-10-26  8:18     ` [dpdk-dev] 回复: " Feifei Wang
2021-10-26  9:43       ` [dpdk-dev] " Ananyev, Konstantin
2021-10-26 12:56         ` Ananyev, Konstantin
2021-10-27  7:04           ` [dpdk-dev] 回复: " Feifei Wang
2021-10-27  7:31             ` Feifei Wang [this message]
2021-10-27 14:47             ` [dpdk-dev] " Ananyev, Konstantin
2021-10-28  6:24               ` [dpdk-dev] 回复: " Feifei Wang
2021-10-26  8:02   ` [dpdk-dev] [PATCH v5 5/5] lib/distributor: use wait event scheme Feifei Wang
2021-10-27  8:10 ` [dpdk-dev] [PATCH v6 0/4] add new definitions for wait scheme Feifei Wang
2021-10-27  8:10   ` [dpdk-dev] [PATCH v6 1/4] eal: " Feifei Wang
2021-10-27  8:10   ` [dpdk-dev] [PATCH v6 2/4] eal: use wait event for read pflock Feifei Wang
2021-10-27  8:10   ` [dpdk-dev] [PATCH v6 3/4] eal: use wait event scheme for mcslock Feifei Wang
2021-10-27 11:16     ` Mattias Rönnblom
2021-10-28  6:32       ` [dpdk-dev] 回复: " Feifei Wang
2021-10-27  8:10   ` [dpdk-dev] [PATCH v6 4/4] lib/distributor: use wait event scheme Feifei Wang
2021-10-27 10:57   ` [dpdk-dev] [PATCH v6 0/4] add new definitions for wait scheme Jerin Jacob
2021-10-28  6:33     ` [dpdk-dev] 回复: " Feifei Wang
2021-10-28  6:56 ` [dpdk-dev] [PATCH v7 0/5] " Feifei Wang
2021-10-28  6:56   ` [dpdk-dev] [PATCH v7 1/5] eal: " Feifei Wang
2021-10-28  7:15     ` Jerin Jacob
2021-10-28  7:40       ` [dpdk-dev] 回复: " Feifei Wang
2021-10-28  7:51         ` [dpdk-dev] " Jerin Jacob
2021-10-28  9:27           ` [dpdk-dev] 回复: " Feifei Wang
2021-10-28 13:14     ` [dpdk-dev] " Ananyev, Konstantin
2021-10-28  6:56   ` [dpdk-dev] [PATCH v7 2/5] eal: use wait event for read pflock Feifei Wang
2021-10-28  6:56   ` [dpdk-dev] [PATCH v7 3/5] eal: use wait event scheme for mcslock Feifei Wang
2021-10-28  7:02     ` Jerin Jacob
2021-10-28  7:14       ` [dpdk-dev] 回复: " Feifei Wang
2021-10-28  6:56   ` [dpdk-dev] [PATCH v7 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration Feifei Wang
2021-10-28 13:15     ` Ananyev, Konstantin
2021-10-28  6:56   ` [dpdk-dev] [PATCH v7 5/5] lib/distributor: use wait event scheme Feifei Wang
2021-10-29  8:20 ` [dpdk-dev] [PATCH v8 0/5] add new definitions for wait scheme Feifei Wang
2021-10-29  8:20   ` [dpdk-dev] [PATCH v8 1/5] eal: " Feifei Wang
2021-10-29 13:54     ` Jerin Jacob
2021-10-31  8:38     ` David Marchand
2021-11-01  2:29       ` [dpdk-dev] 回复: " Feifei Wang
2021-10-29  8:20   ` [dpdk-dev] [PATCH v8 2/5] eal: use wait event for read pflock Feifei Wang
2021-10-29 13:55     ` Jerin Jacob
2021-10-31  8:37     ` David Marchand
2021-10-29  8:20   ` [dpdk-dev] [PATCH v8 3/5] eal: use wait event scheme for mcslock Feifei Wang
2021-10-29 13:55     ` Jerin Jacob
2021-10-31  8:37     ` David Marchand
2021-10-29  8:20   ` [dpdk-dev] [PATCH v8 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration Feifei Wang
2021-10-31  8:37     ` David Marchand
2021-10-29  8:20   ` [dpdk-dev] [PATCH v8 5/5] lib/distributor: use wait event scheme Feifei Wang
2021-10-29 13:58     ` Jerin Jacob
2021-10-31  8:38       ` David Marchand
2021-11-01 12:44       ` David Hunt
2021-11-01  6:00 ` [dpdk-dev] [PATCH v9 0/5] add new helper for wait scheme Feifei Wang
2021-11-01  6:00   ` [dpdk-dev] [PATCH v9 1/5] eal: add a new generic " Feifei Wang
2021-11-01  6:00   ` [dpdk-dev] [PATCH v9 2/5] pflock: use wait until scheme for read pflock Feifei Wang
2021-11-03 14:46     ` David Marchand
2021-11-04  1:24       ` [dpdk-dev] 回复: " Feifei Wang
2021-11-01  6:00   ` [dpdk-dev] [PATCH v9 3/5] mcslock: use wait until scheme for mcslock Feifei Wang
2021-11-01  6:00   ` [dpdk-dev] [PATCH v9 4/5] bpf: use wait until scheme for Rx/Tx iteration Feifei Wang
2021-11-01  6:00   ` [dpdk-dev] [PATCH v9 5/5] distributor: use wait until scheme Feifei Wang
2021-11-01 16:05     ` Pattan, Reshma
2021-11-02  2:00       ` [dpdk-dev] 回复: " Feifei Wang
2021-11-03 14:55   ` [dpdk-dev] [PATCH v9 0/5] add new helper for wait scheme David Marchand

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