DPDK patches and discussions
 help / color / mirror / Atom feed
From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: Feifei Wang <Feifei.Wang2@arm.com>, Ruifeng Wang <Ruifeng.Wang@arm.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, nd <nd@arm.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [RFC PATCH v3 1/5] eal: add new definitions for wait scheme
Date: Wed, 13 Oct 2021 15:03:56 +0000
Message-ID: <DM6PR11MB4491424E1DBA460026B5FD729AB79@DM6PR11MB4491.namprd11.prod.outlook.com> (raw)
In-Reply-To: <DB9PR08MB6923C02888AAD5294CC992D8C8B69@DB9PR08MB6923.eurprd08.prod.outlook.com>

> 
> [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(...); \
...

> 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.


  reply	other threads:[~2021-10-13 15:05 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         ` Ananyev, Konstantin [this message]
2021-10-13 17:00           ` [dpdk-dev] " 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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=DM6PR11MB4491424E1DBA460026B5FD729AB79@DM6PR11MB4491.namprd11.prod.outlook.com \
    --to=konstantin.ananyev@intel.com \
    --cc=Feifei.Wang2@arm.com \
    --cc=Ruifeng.Wang@arm.com \
    --cc=dev@dpdk.org \
    --cc=nd@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror http://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ http://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git