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From: Phil Yang <Phil.Yang@arm.com>
To: "Carrillo, Erik G" <erik.g.carrillo@intel.com>,
	Stephen Hemminger <stephen@networkplumber.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"drc@linux.vnet.ibm.com" <drc@linux.vnet.ibm.com>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	Ruifeng Wang <Ruifeng.Wang@arm.com>,
	Dharmik Thakkar <Dharmik.Thakkar@arm.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH 2/3] eventdev: use c11 atomics for lcore timer armed flag
Date: Sun, 28 Jun 2020 16:32:04 +0000	[thread overview]
Message-ID: <VE1PR08MB4640480638A421461872978DE9910@VE1PR08MB4640.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <CY4PR1101MB2118B18DB87C1CD779201305B9940@CY4PR1101MB2118.namprd11.prod.outlook.com>

> -----Original Message-----
> From: Carrillo, Erik G <erik.g.carrillo@intel.com>
> Sent: Wednesday, June 24, 2020 5:32 AM
> To: Stephen Hemminger <stephen@networkplumber.org>; Phil Yang
> <Phil.Yang@arm.com>
> Cc: dev@dpdk.org; drc@linux.vnet.ibm.com; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>; Dharmik Thakkar <Dharmik.Thakkar@arm.com>;
> nd <nd@arm.com>
> Subject: RE: [dpdk-dev] [PATCH 2/3] eventdev: use c11 atomics for lcore
> timer armed flag
> 
> > -----Original Message-----
> > From: Stephen Hemminger <stephen@networkplumber.org>
> > Sent: Tuesday, June 23, 2020 4:20 PM
> > To: Phil Yang <phil.yang@arm.com>
> > Cc: dev@dpdk.org; Carrillo, Erik G <erik.g.carrillo@intel.com>;
> > drc@linux.vnet.ibm.com; honnappa.nagarahalli@arm.com;
> > ruifeng.wang@arm.com; dharmik.thakkar@arm.com; nd@arm.com
> > Subject: Re: [dpdk-dev] [PATCH 2/3] eventdev: use c11 atomics for lcore
> > timer armed flag
> >
> > On Fri, 12 Jun 2020 19:19:57 +0800
> > Phil Yang <phil.yang@arm.com> wrote:
> >
> > >  	/* Track which cores have actually armed a timer */
> > >  	struct {
> > > -		rte_atomic16_t v;
> > > +		int16_t v;
> > >  	} __rte_cache_aligned in_use[RTE_MAX_LCORE];
> >
> > Do you really need this to be cache aligned (ie one per line)?
> 
> I believe I did this originally to keep a cache line from bouncing when two
> different cores are arming timers, so it's not strictly necessary.

Yeah, if we remove it, these per core variables might cause a false sharing issue between threads. 
That will hurt performance.

> 
> > Why have a signed value for a reference count? Shouldn't it be unsigned?

Yes. It should be unsigned in the new code. 
I will update it in the next version.

Thanks,
Phil

  reply	other threads:[~2020-06-28 16:32 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-12 11:19 [dpdk-dev] [PATCH 1/3] eventdev: fix race condition on timer list counter Phil Yang
2020-06-12 11:19 ` [dpdk-dev] [PATCH 2/3] eventdev: use c11 atomics for lcore timer armed flag Phil Yang
2020-06-23 21:01   ` Carrillo, Erik G
2020-06-28 16:12     ` Phil Yang
2020-06-23 21:20   ` Stephen Hemminger
2020-06-23 21:31     ` Carrillo, Erik G
2020-06-28 16:32       ` Phil Yang [this message]
2020-06-12 11:19 ` [dpdk-dev] [PATCH 3/3] eventdev: relax smp barriers with c11 atomics Phil Yang
2020-06-22 10:12   ` Phil Yang
2020-06-23 19:38     ` Carrillo, Erik G
2020-06-28 17:33       ` Phil Yang
2020-06-29 18:07         ` Carrillo, Erik G
2020-06-18 15:17 ` [dpdk-dev] [PATCH 1/3] eventdev: fix race condition on timer list counter Carrillo, Erik G
2020-06-18 18:25   ` Honnappa Nagarahalli
2020-06-22  9:48     ` Phil Yang
2020-07-01 11:22       ` Jerin Jacob
2020-07-02  3:28         ` Phil Yang
2020-07-02  3:26     ` Phil Yang
2020-07-02  3:56       ` Honnappa Nagarahalli
2020-07-02 21:15         ` Carrillo, Erik G
2020-07-02 21:30           ` Honnappa Nagarahalli
2020-06-22  9:09   ` Phil Yang
2020-07-02  5:26 ` [dpdk-dev] [PATCH v2 1/4] " Phil Yang
2020-07-02  5:26   ` [dpdk-dev] [PATCH v2 2/4] eventdev: use c11 atomics for lcore timer armed flag Phil Yang
2020-07-02 20:21     ` Carrillo, Erik G
2020-07-02  5:26   ` [dpdk-dev] [PATCH v2 3/4] eventdev: remove redundant code Phil Yang
2020-07-03  3:35     ` Dharmik Thakkar
2020-07-02  5:26   ` [dpdk-dev] [PATCH v2 4/4] eventdev: relax smp barriers with c11 atomics Phil Yang
2020-07-02 20:30     ` Carrillo, Erik G
2020-07-03 10:50       ` Jerin Jacob
2020-07-06 10:04     ` Thomas Monjalon
2020-07-06 15:32       ` Phil Yang
2020-07-06 15:40         ` Thomas Monjalon
2020-07-07 11:13   ` [dpdk-dev] [PATCH v3 1/4] eventdev: fix race condition on timer list counter Phil Yang
2020-07-07 11:13     ` [dpdk-dev] [PATCH v3 2/4] eventdev: use C11 atomics for lcore timer armed flag Phil Yang
2020-07-07 11:13     ` [dpdk-dev] [PATCH v3 3/4] eventdev: remove redundant code Phil Yang
2020-07-07 11:13     ` [dpdk-dev] [PATCH v3 4/4] eventdev: relax smp barriers with C11 atomics Phil Yang
2020-07-07 14:29       ` Jerin Jacob
2020-07-07 15:56         ` Phil Yang
2020-07-07 15:54     ` [dpdk-dev] [PATCH v4 1/4] eventdev: fix race condition on timer list counter Phil Yang
2020-07-07 15:54       ` [dpdk-dev] [PATCH v4 2/4] eventdev: use C11 atomics for lcore timer armed flag Phil Yang
2020-07-07 15:54       ` [dpdk-dev] [PATCH v4 3/4] eventdev: remove redundant code Phil Yang
2020-07-07 15:54       ` [dpdk-dev] [PATCH v4 4/4] eventdev: relax smp barriers with C11 atomics Phil Yang
2020-07-08 13:30       ` [dpdk-dev] [PATCH v4 1/4] eventdev: fix race condition on timer list counter Jerin Jacob
2020-07-08 15:01         ` Thomas Monjalon

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