> -----Original Message----- > From: Richardson, Bruce > Sent: Monday, December 22, 2014 10:46 AM > To: Liang, Cunming > Cc: Walukiewicz, Miroslaw; dev at dpdk.org > Subject: Re: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore > > 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? > I would prefer keeping the RTE_MAX_LCORES as Bruce suggests and determine the HW core on base of following condition if we really have to know this.
int num_cores_online = count of cores encountered in the core mask provided by cmdline parameter Rte_lcore_id() < num_cores_online -> physical core (pthread first started on the core) Rte_lcore_id() >= num_cores_online -> pthread created by rte_pthread_create Mirek > /Bruce