Messages in this thread | | | Date | Tue, 9 Oct 2012 22:28:21 +0530 | Subject | Re: [RFC PATCH 02/10] sched: Task placement for heterogeneous systems based on task load-tracking | From | Viresh Kumar <> |
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On 9 October 2012 21:26, Morten Rasmussen <Morten.Rasmussen@arm.com> wrote: > On Thu, Oct 04, 2012 at 07:02:03AM +0100, Viresh Kumar wrote: >> On 22 September 2012 00:02, <morten.rasmussen@arm.com> wrote:
>> > SCHED_HMP requires that the platform implements arch_get_hmp_domains() >> > which should set up the platform specific list of hmp_domains. It is >> > also assumed that the platform disables SD_LOAD_BALANCE for the >> > appropriate sched_domains. >> >> An explanation of this requirement would be helpful here. > > Yes. This is to prevent the load-balancer from moving tasks between > hmp_domains. This will be done exclusively by SCHED_HMP instead to > implement a strict task migration policy and avoid changing the > load-balancer behaviour. The load-balancer will take care of > load-balacing within each hmp_domain.
Honestly speaking i understood this point now and earlier it wasn't clear to me :)
What would be ideal is to put this information in the comment just before we re-define other SCHED_*** domains where we disable balancing. And keep it in the commit log too.
>> > +struct hmp_domain { >> > + struct cpumask cpus; >> > + struct list_head hmp_domains; >> >> Probably need a better name here. domain_list? > > Yes. hmp_domain_list would be better and stick with the hmp_* naming > convention.
IMHO hmp_ would be better for global names, but names of variables enclosed within another hmp_*** data type don't actually need hmp_**, as this is implicity.
i.e. struct hmp_domain { struct cpumask cpus; struct list_head domain_list; }
would be better than struct list_head hmp domain_list;
as the parent structure already have hmp_***. So whatever is inside the struct is obviously hmp specific.
>> > +/* Setup hmp_domains */ >> > +static int __init hmp_cpu_mask_setup(void) >> >> How should we interpret its return value? Can you mention what does 0 & 1 mean >> here? >> > > Returns 0 if domain setup failed, i.e. the domain list is empty, and 1 > otherwise.
Helpful. Please mention this in function comment in your next revision.
>> > +{ >> > + char buf[64]; >> > + struct hmp_domain *domain; >> > + struct list_head *pos; >> > + int dc, cpu;
>> > + /* Print hmp_domains */ >> > + dc = 0; >> >> Should be done during definition of dc.
You missed this ??
>> > + for_each_cpu_mask(cpu, domain->cpus) { >> > + per_cpu(hmp_cpu_domain, cpu) = domain; >> > + } >> >> Should use hmp_cpu_domain(cpu) here. Also no need of {} for single >> line loop.
??
>> > + dc++; >> >> You aren't using it... Only for testing? Should we remove it from mainline >> patchset and keep it locally? >> > > I'm using it in the pr_debug line a little earlier. It is used for > enumerating the hmp_domains.
My mistake :(
>> > +/* Check if cpu is in fastest hmp_domain */ >> > +static inline unsigned int hmp_cpu_is_fastest(int cpu) >> > +{ >> > + struct list_head *pos; >> > + >> > + pos = &hmp_cpu_domain(cpu)->hmp_domains; >> > + return pos == hmp_domains.next; >> >> better create list_is_first() for this. > > I had the same thought, but I see that as a separate patch that should > be submitted separately.
Correct. So better send it now, so that it is included before you send your next version. :)
-- viresh
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