diff options
| author | Liao Chang <liaochang1@huawei.com> | 2023-08-26 12:57:43 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2023-08-29 21:41:29 +0300 |
| commit | 4c2fdf7393647a7b01a83f49c4a331d562016640 (patch) | |
| tree | cedfea0660e686d0049467d67d8f4fb5ec9e01ae /drivers/cpufreq | |
| parent | 916f13884042f615cfbfc0b42cc68dadee826f2a (diff) | |
| download | linux-4c2fdf7393647a7b01a83f49c4a331d562016640.tar.xz | |
cpufreq: pcc: Fix the potentinal scheduling delays in target_index()
pcc_cpufreq_target():
cpufreq_freq_transition_begin();
spin_lock(&pcc_lock);
[critical section]
cpufreq_freq_transition_end();
spin_unlock(&pcc_lock);
Above code has a performance issue, consider that Task0 executes
'cpufreq_freq_transition_end()' to wake Task1 and preempted imediatedly
without releasing 'pcc_lock', then Task1 needs to wait for Task0 to
release 'pcc_lock'. In the worst case, this locking order can result in
Task1 wasting two scheduling rounds before it can enter the critical
section.
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/pcc-cpufreq.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c index 84fe37def0f1..6f8b5ea7aeae 100644 --- a/drivers/cpufreq/pcc-cpufreq.c +++ b/drivers/cpufreq/pcc-cpufreq.c @@ -232,8 +232,8 @@ static int pcc_cpufreq_target(struct cpufreq_policy *policy, status = ioread16(&pcch_hdr->status); iowrite16(0, &pcch_hdr->status); - cpufreq_freq_transition_end(policy, &freqs, status != CMD_COMPLETE); spin_unlock(&pcc_lock); + cpufreq_freq_transition_end(policy, &freqs, status != CMD_COMPLETE); if (status != CMD_COMPLETE) { pr_debug("target: FAILED for cpu %d, with status: 0x%x\n", |