Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH v2] sched: sched_domain fix highest_flag_domain function | Date | Tue, 27 Oct 2020 10:47:13 +0000 |
| |
On 27/10/20 09:57, Dietmar Eggemann wrote: > On 27/10/2020 04:32, Xuewen Yan wrote: >> the highest_flag_domain is to search the highest sched_domain >> containing flag, but if the lower sched_domain didn't contain >> the flag, but the higher sched_domain contains the flag, the >> function will return NULL instead of the higher sched_domain. >> >> For example: >> In MC domain : no SD_ASYM_CPUCAPACITY flag; >> In DIE domain : containing SD_ASYM_CPUCAPACITY flag; >> the "highest_flag_domain(cpu, SD_ASYM_CPUCAPACITY)" will return NULL. >> >> Signed-off-by: Xuewen Yan <xuewen.yan94@gmail.com> >> --- >> kernel/sched/sched.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h >> index 28709f6..2c7c566 100644 >> --- a/kernel/sched/sched.h >> +++ b/kernel/sched/sched.h >> @@ -1427,7 +1427,7 @@ static inline struct sched_domain *highest_flag_domain(int cpu, int flag) >> >> for_each_domain(cpu, sd) { >> if (!(sd->flags & flag)) >> - break; >> + continue; >> hsd = sd; >> } > > We distinguish between SDF_SHARED_PARENT and SDF_SHARED_CHILD SD flags. > > 1 SD_FLAG(*SD_ASYM_CPUCAPACITY*, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) > 2 SD_FLAG(SD_SERIALIZE, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) > 3 SD_FLAG(SD_OVERLAP, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) > 4 SD_FLAG(SD_NUMA, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) > > 1 SD_FLAG(SD_BALANCE_NEWIDLE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > 2 SD_FLAG(SD_BALANCE_EXEC, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > 3 SD_FLAG(SD_BALANCE_FORK, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > 4 SD_FLAG(SD_BALANCE_WAKE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > 5 82 SD_FLAG(SD_WAKE_AFFINE, SDF_SHARED_CHILD) > 6 SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > 7 SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > 8 SD_FLAG(SD_ASYM_PACKING, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) > > We call lowest_flag_domain() on SDF_SHARED_PARENT and > highest_flag_domain() on SDF_SHARED_CHILD SD flags. > > 1 sd = lowest_flag_domain(cpu, SD_NUMA); > 2 sd = lowest_flag_domain(cpu, *SD_ASYM_CPUCAPACITY*); > > 1 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); > 2 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
Spot on!
In some of my earliest instrumentation patches I had a SCHED_WARN_ON() for when highest_flag_domain() is passed an SDF_SHARED_PARENT flag (for some reason I don't have the equivalent for lowest_flag_domain() in that branch). I had ditched that as it didn't seem that useful, but perhaps that wasn't so accurate :)
| |