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