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author | Ricardo Neri <ricardo.neri-calderon@linux.intel.com> | 2021-09-10 18:18:14 -0700 |
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committer | Peter Zijlstra <peterz@infradead.org> | 2021-10-05 15:51:59 +0200 |
commit | 183b8ec38f1ec6c1f8419375303bf1d09a2b8369 (patch) | |
tree | a22f632334a802f615c816b55a1603ea975c2a19 /arch/x86/kernel/itmt.c | |
parent | 1a7243ca4074beed97b68d7235a6e34862fc2cd6 (diff) | |
download | linux-stable-183b8ec38f1ec6c1f8419375303bf1d09a2b8369.tar.gz linux-stable-183b8ec38f1ec6c1f8419375303bf1d09a2b8369.tar.bz2 linux-stable-183b8ec38f1ec6c1f8419375303bf1d09a2b8369.zip |
x86/sched: Decrease further the priorities of SMT siblings
When scheduling, it is better to prefer a separate physical core rather
than the SMT sibling of a high priority core. The existing formula to
compute priorities takes such fact in consideration. There may exist,
however, combinations of priorities (i.e., maximum frequencies) in which
the priority of high-numbered SMT siblings of high-priority cores collides
with the priority of low-numbered SMT siblings of low-priority cores.
Consider for instance an SMT2 system with CPUs [0, 1] with priority 60 and
[2, 3] with priority 30(CPUs in brackets are SMT siblings. In such a case,
the resulting priorities would be [120, 60], [60, 30]. Thus, to ensure
that CPU2 has higher priority than CPU1, divide the raw priority by the
squared SMT iterator. The resulting priorities are [120, 30]. [60, 15].
Originally-by: Len Brown <len.brown@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210911011819.12184-2-ricardo.neri-calderon@linux.intel.com
Diffstat (limited to 'arch/x86/kernel/itmt.c')
-rw-r--r-- | arch/x86/kernel/itmt.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c index 1afbdd1dd777..9ff480e94511 100644 --- a/arch/x86/kernel/itmt.c +++ b/arch/x86/kernel/itmt.c @@ -198,7 +198,7 @@ void sched_set_itmt_core_prio(int prio, int core_cpu) * of the priority chain and only used when * all other high priority cpus are out of capacity. */ - smt_prio = prio * smp_num_siblings / i; + smt_prio = prio * smp_num_siblings / (i * i); per_cpu(sched_core_priority, cpu) = smt_prio; i++; } |