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From: Phil Yang <Phil.Yang@arm.com>
To: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>,
	Harry van Haaren <harry.van.haaren@intel.com>,
	Jerin Jacob <jerin.jacob@caviumnetworks.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"stable@dpdk.org" <stable@dpdk.org>, nd <nd@arm.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] eal: fix lcore state bug
Date: Thu, 30 Apr 2020 02:54:13 +0000	[thread overview]
Message-ID: <VE1PR08MB46405361FE30F51A917FFE63E9AA0@VE1PR08MB4640.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <ce173f19-031a-524e-ab0e-9b8a30348d38@partner.samsung.com>

> -----Original Message-----
> From: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>
> Sent: Thursday, April 30, 2020 5:32 AM
> To: Phil Yang <Phil.Yang@arm.com>; Harry van Haaren
> <harry.van.haaren@intel.com>; Jerin Jacob
> <jerin.jacob@caviumnetworks.com>
> Cc: dev@dpdk.org; stable@dpdk.org; nd <nd@arm.com>
> Subject: Re: [dpdk-dev] [PATCH] eal: fix lcore state bug
> 
> Hi Phil,
> 
> W dniu 29.04.2020 o 17:07, Phil Yang pisze:
> > Hi Lukasz,
> >
> >> -----Original Message-----
> >> From: dev <dev-bounces@dpdk.org> On Behalf Of Lukasz Wojciechowski
> >> Sent: Tuesday, April 28, 2020 9:22 AM
> >> To: Harry van Haaren <harry.van.haaren@intel.com>; Jerin Jacob
> >> <jerin.jacob@caviumnetworks.com>
> >> Cc: dev@dpdk.org; l.wojciechow@partner.samsung.com;
> stable@dpdk.org
> >> Subject: [dpdk-dev] [PATCH] eal: fix lcore state bug
> >>
> >> The rte_service_lcore_reset_all function stops execution of services
> >> on all lcores and switches them back from ROLE_SERVICE to ROLE_RTE.
> >> However the thread loop for slave lcores (eal_thread_loop) distincts
> these
> >> roles to set lcore state after processing delegated function.
> >> It sets WAIT state for ROLE_SERVICE, but FINISHED for ROLE_RTE.
> >> So changing the role to RTE before stopping work in slave lcores
> >> causes lcores to end in FINISHED state. That is why the rte_eal_lcore_wait
> >> must be run after rte_service_lcore_reset_all to bring back lcores to
> >> launchable (WAIT) state.
> > Is that make sense to call rte_eal_mp_wait_lcore() inside
> rte_serice_lcore_reset_all() ?
> 
> yeah, I thought about it and in my opinion the answer is no, because if
> the function run on slave lcore is in FINISHED state it means, that
> someone can still read the value returned by the function and the only
> one who can be interested in the value is the one that delegated the
> service.
> 
> If we will wait for lcores to end their jobs, read the values and switch
> them to WAIT state, the values will be lost. The application might need
> to read them. We cannot take this possibility from it.

Yeah. I think that is a good point.

Reviewed-by: Phil Yang <phil.yang@arm.com>

> 
> > <snip>
> >
> > Thanks,
> > Phil
> 
> --
> 
> Lukasz Wojciechowski
> Principal Software Engineer
> 
> Samsung R&D Institute Poland
> Samsung Electronics
> Office +48 22 377 88 25
> l.wojciechow@partner.samsung.com


  reply	other threads:[~2020-04-30  2:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200428012204eucas1p120a84e501d0d64145c21476cd2562f36@eucas1p1.samsung.com>
2020-04-28  1:21 ` [dpdk-stable] " Lukasz Wojciechowski
2020-04-29  3:11   ` [dpdk-stable] [dpdk-dev] " Ruifeng Wang
2020-04-29 15:07   ` Phil Yang
2020-04-29 21:32     ` Lukasz Wojciechowski
2020-04-30  2:54       ` Phil Yang [this message]
2020-04-30  9:06         ` Lukasz Wojciechowski
2020-05-08 16:12         ` Van Haaren, Harry
2020-05-08 17:04           ` Lukasz Wojciechowski
2020-05-18 18:25   ` [dpdk-stable] " Lukasz Wojciechowski
2020-05-18 18:39     ` David Marchand
2020-05-18 18:43       ` Lukasz Wojciechowski
2020-05-20 11:40         ` Van Haaren, Harry
2020-05-20 12:47           ` Lukasz Wojciechowski
     [not found]   ` <CGME20200708133748eucas1p2dbe34d8605d8f618559daee9cbeaa73d@eucas1p2.samsung.com>
2020-07-08 13:37     ` [dpdk-stable] [PATCH v2] " Lukasz Wojciechowski
2020-07-08 14:52       ` Van Haaren, Harry
2020-07-08 17:10         ` David Marchand
2020-07-08 19:37           ` Lukasz Wojciechowski

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