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From: Feifei Wang <Feifei.Wang2@arm.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	Ruifeng Wang <Ruifeng.Wang@arm.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, nd <nd@arm.com>, nd <nd@arm.com>,
	nd <nd@arm.com>
Subject: [dpdk-dev] 回复:  [RFC PATCH v3 1/5] eal: add new definitions for wait scheme
Date: Thu, 14 Oct 2021 03:08:09 +0000
Message-ID: <DB9PR08MB69238C710EA067653EDC5A30C8B89@DB9PR08MB6923.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <DM6PR11MB4491424E1DBA460026B5FD729AB79@DM6PR11MB4491.namprd11.prod.outlook.com>

> -----邮件原件-----
> 发件人: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> 发送时间: Wednesday, October 13, 2021 11:04 PM
> 收件人: Feifei Wang <Feifei.Wang2@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>
> 抄送: dev@dpdk.org; nd <nd@arm.com>; nd <nd@arm.com>
> 主题: RE: [dpdk-dev] [RFC PATCH v3 1/5] eal: add new definitions for wait
> scheme
> 
> >
> > [snip]
> >
> > > > diff --git a/lib/eal/include/generic/rte_pause.h
> > > > b/lib/eal/include/generic/rte_pause.h
> > > > index 668ee4a184..4e32107eca 100644
> > > > --- a/lib/eal/include/generic/rte_pause.h
> > > > +++ b/lib/eal/include/generic/rte_pause.h
> > > > @@ -111,6 +111,84 @@ rte_wait_until_equal_64(volatile uint64_t
> > > > *addr,
> > > uint64_t expected,
> > > >  	while (__atomic_load_n(addr, memorder) != expected)
> > > >  		rte_pause();
> > > >  }
> > > > +
> > > > +/*
> > > > + * Wait until a 16-bit *addr breaks the condition, with a relaxed
> > > > +memory
> > > > + * ordering model meaning the loads around this API can be reordered.
> > > > + *
> > > > + * @param addr
> > > > + *  A pointer to the memory location.
> > > > + * @param mask
> > > > + *  A mask of value bits in interest
> > > > + * @param expected
> > > > + *  A 16-bit expected value to be in the memory location.
> > > > + * @param cond
> > > > + *  A symbol representing the condition (==, !=).
> > > > + * @param memorder
> > > > + *  Two different memory orders that can be specified:
> > > > + *  __ATOMIC_ACQUIRE and __ATOMIC_RELAXED. These map to
> > > > + *  C++11 memory orders with the same names, see the C++11
> > > > +standard or
> > > > + *  the GCC wiki on atomic synchronization for detailed definition.
> > > > + */
> > >
> > > Hmm, so now we have 2 APIs doing similar thing:
> > > rte_wait_until_equal_n() and rte_wait_event_n().
> > > Can we probably unite them somehow?
> > > At least make rte_wait_until_equal_n() to use rte_wait_event_n()
> underneath.
> > >
> > You are right. We plan to change rte_wait_until_equal API after this
> > new scheme is achieved.  And then, we will merge wait_unil into
> > wait_event definition in the next new patch series.
> >
> > > > +#define rte_wait_event_16(addr, mask, expected, cond, memorder)
> > > 		       \
> > > > +do {
> 	       \
> > > > +	assert(memorder == __ATOMIC_ACQUIRE || memorder ==
> > > > +__ATOMIC_RELAXED);  \
> > >
> > > And why user is not allowed to use __ATOMIC_SEQ_CST here?
> > Actually this is just a load operation, and acquire here is enough to
> > make sure 'load addr value' can be before other operations.
> >
> > > BTW, if we expect memorder to always be a constant, might be better
> > > BUILD_BUG_ON()?
> > If I understand correctly, you means we can replace 'assert' by
> 'build_bug_on':
> > RTE_BUILD_BUG_ON(memorder != __ATOMIC_ACQUIRE && memorder
> > !=__ATOMIC_RELAXED);
> 
> Yes, that was my thought.
> In that case I think we should be able to catch wrong memorder at compilation
> stage.
> 
> >
> > >
> > > > +									       \
> > > > +	while ((__atomic_load_n(addr, memorder) & mask) cond expected)
> > > 	       \
> > > > +		rte_pause();						       \
> > > > +} while (0)
> > >
> > > Two thoughts with these macros:
> > > 1. It is a goof practise to put () around macro parameters in the macro
> body.
> > > Will save from a lot of unexpected troubles.
> > > 2. I think these 3 macros can be united into one.
> > > Something like:
> > >
> > > #define rte_wait_event(addr, mask, expected, cond, memorder) do {\
> > >         typeof (*(addr)) val = __atomic_load_n((addr), (memorder)); \
> > >         if ((val & (typeof(val))(mask)) cond (typeof(val))(expected)) \
> > >                 break; \
> > >         rte_pause(); \
> > > } while (1);
> > For this point, I think it is due to different size need to use
> > different assembly instructions in arm architecture. For example, load
> > 16 bits instruction is "ldxrh %w[tmp], [%x[addr]"
> > load 32 bits instruction is " ldxr %w[tmp], [%x[addr]"
> > load 64 bits instruction is " ldxr %x[tmp], [%x[addr] "
> 
> Ok, but it could be then something like that for arm specific code:
> if (sizeof(val) == sizeof(uint16_t)) \
> 	__LOAD_EXC_16(...); \
> else if (sizeof(val) == sizeof(uint32_t)) \
> 	__LOAD_EXC_32(...); \
> else if (sizeof(val) == sizeof(uint64_t)) \
> 	__LOAD_EXC_64(...); \
> ...
> 
I thinks we should use "addr" as judgement:

rte_wait_event(addr, mask, expected, cond, memorder)
if (sizeof(*addr)) == sizeof(uint16_t) 
	uint16_t value                                                         \
	assert(memorder == __ATOMIC_ACQUIRE || memorder == __ATOMIC_RELAXED);  \
	__LOAD_EXC_16(addr, value, memorder)				       \
	if ((value & mask) cond expected) {				       \
		__SEVL()						       \
		do {							       \
			__WFE()						       \
			__LOAD_EXC_16(addr, value, memorder)		       \
		} while ((value & mask) cond expected);			       \
	}	
if (sizeof(*addr)) == sizeof(uint32_t) 
	..........
if (sizeof(*addr)) == sizeof(uint64_t) 
	...........

> > And for consistency, we also use 3 APIs in generic path.
> Honestly, even one multi-line macro doesn't look nice.
> Having 3 identical ones looks even worse.


  parent reply	other threads:[~2021-10-14  3:08 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 [this message]
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
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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