From: Stephen Hemminger <stephen@networkplumber.org>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore
Date: Mon, 22 Dec 2014 10:28:52 -0800 [thread overview]
Message-ID: <20141222102852.7e6d5e81@urahara> (raw)
In-Reply-To: <20141222094603.GA1768@bricha3-MOBL3>
On Mon, 22 Dec 2014 09:46:03 +0000
Bruce Richardson <bruce.richardson@intel.com> wrote:
> On Mon, Dec 22, 2014 at 01:51:27AM +0000, Liang, Cunming wrote:
> > ...
> > > I'm conflicted on this one. However, I think far more applications would be
> > > broken
> > > to start having to use thread_id in place of an lcore_id than would be broken
> > > by having the lcore_id no longer actually correspond to a core.
> > > I'm actually struggling to come up with a large number of scenarios where it's
> > > important to an app to determine the cpu it's running on, compared to the large
> > > number of cases where you need to have a data-structure per thread. In DPDK
> > > libs
> > > alone, you see this assumption that lcore_id == thread_id a large number of
> > > times.
> > >
> > > Despite the slight logical inconsistency, I think it's better to avoid introducing
> > > a thread-id and continue having lcore_id representing a unique thread.
> > >
> > > /Bruce
> >
> > Ok, I understand it.
> > I list the implicit meaning if using lcore_id representing the unique thread.
> > 1). When lcore_id less than RTE_MAX_LCORE, it still represents the logical core id.
> > 2). When lcore_id large equal than RTE_MAX_LCORE, it represents an unique id for thread.
> > 3). Most of APIs(except rte_lcore_id()) in rte_lcore.h suggest to be used only in CASE 1)
> > 4). rte_lcore_id() can be used in CASE 2), but the return value no matter represent a logical core id.
> >
> > If most of us feel it's acceptable, I'll prepare for the RFC v2 base on this conclusion.
> >
> > /Cunming
>
> Sorry, I don't like that suggestion either, as having lcore_id values greater
> than RTE_MAX_LCORE is terrible, as how will people know how to dimension arrays
> to be indexes by lcore id? Given the choice, if we are not going to just use
> lcore_id as a generic thread id, which is always between 0 and RTE_MAX_LCORE
> we can look to define a new thread_id variable to hold that. However, it should
> have a bounded range.
> From an ease-of-porting perspective, I still think that the simplest option is to
> use the existing lcore_id and accept the fact that it's now a thread id rather
> than an actual physical lcore. Question is, is would that cause us lots of issues
> in the future?
>
> /Bruce
The current rte_lcore_id() has different meaning the thread. Your proposal will
break code that uses lcore_id to do per-cpu statistics and the lcore_config
code in the samples.
q
next prev parent reply other threads:[~2014-12-22 18:29 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-11 2:04 Cunming Liang
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 1/7] eal: add linear thread id as pthread-local variable Cunming Liang
2014-12-16 7:00 ` Qiu, Michael
2014-12-22 19:02 ` Ananyev, Konstantin
2014-12-23 9:56 ` Liang, Cunming
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 2/7] mempool: use linear-tid as mempool cache index Cunming Liang
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 3/7] ring: use linear-tid as ring debug stats index Cunming Liang
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 4/7] eal: add simple API for multi-pthread Cunming Liang
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 5/7] testpmd: support multi-pthread mode Cunming Liang
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 6/7] sample: add new sample for multi-pthread Cunming Liang
2014-12-11 2:04 ` [dpdk-dev] [RFC PATCH 7/7] eal: macro for cpuset w/ or w/o CPU_ALLOC Cunming Liang
2014-12-11 2:54 ` [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore Jayakumar, Muthurajan
2014-12-11 9:56 ` Walukiewicz, Miroslaw
2014-12-12 5:44 ` Liang, Cunming
2014-12-15 11:10 ` Walukiewicz, Miroslaw
2014-12-15 11:53 ` Liang, Cunming
2014-12-18 12:20 ` Walukiewicz, Miroslaw
2014-12-18 14:32 ` Bruce Richardson
2014-12-18 15:11 ` Olivier MATZ
2014-12-18 16:04 ` Bruce Richardson
2014-12-18 16:15 ` Stephen Hemminger
2014-12-19 1:28 ` Liang, Cunming
2014-12-19 10:03 ` Bruce Richardson
2014-12-22 1:51 ` Liang, Cunming
2014-12-22 9:46 ` Bruce Richardson
2014-12-22 10:01 ` Walukiewicz, Miroslaw
2014-12-23 9:45 ` Liang, Cunming
2014-12-22 18:28 ` Stephen Hemminger [this message]
2014-12-23 9:19 ` Walukiewicz, Miroslaw
2014-12-23 9:23 ` Bruce Richardson
2014-12-23 9:51 ` Liang, Cunming
2015-01-08 17:05 ` Ananyev, Konstantin
2015-01-08 17:23 ` Richardson, Bruce
2015-01-09 9:51 ` Liang, Cunming
2015-01-09 9:40 ` Liang, Cunming
2015-01-09 11:52 ` Ananyev, Konstantin
2015-01-09 9:45 ` Liang, Cunming
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