From: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
To: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org
Cc: rjw@rjwysocki.net, viresh.kumar@linaro.org,
linux-pm@vger.kernel.org, pc@us.ibm.com, anton@samba.org,
ego@linux.vnet.ibm.com, shreyas@linux.vnet.ibm.com,
bsingharora@gmail.com, mpe@ellerman.id.au,
Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Subject: [PATCH v8 3/6] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path
Date: Wed, 3 Feb 2016 01:11:39 +0530 [thread overview]
Message-ID: <1454442102-1229-4-git-send-email-shilpa.bhat@linux.vnet.ibm.com> (raw)
In-Reply-To: <1454442102-1229-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com>
cpu_to_chip_id() does a DT walk through to find out the chip id by
taking a contended device tree lock. This adds an unnecessary overhead
in a hot path. So instead of calling cpu_to_chip_id() everytime cache
the chip ids for all cores in the array 'core_to_chip_map' and use it
in the hotpath.
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
---
No changes from v7.
drivers/cpufreq/powernv-cpufreq.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index a271b0f..c670314 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -43,6 +43,7 @@
static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
static bool rebooting, throttled, occ_reset;
+static unsigned int *core_to_chip_map;
static struct chip {
unsigned int id;
@@ -313,13 +314,14 @@ static inline unsigned int get_nominal_index(void)
static void powernv_cpufreq_throttle_check(void *data)
{
unsigned int cpu = smp_processor_id();
+ unsigned int chip_id = core_to_chip_map[cpu_core_index_of_thread(cpu)];
unsigned long pmsr;
int pmsr_pmax, i;
pmsr = get_pmspr(SPRN_PMSR);
for (i = 0; i < nr_chips; i++)
- if (chips[i].id == cpu_to_chip_id(cpu))
+ if (chips[i].id == chip_id)
break;
/* Check for Pmax Capping */
@@ -559,19 +561,29 @@ static int init_chip_info(void)
unsigned int chip[256];
unsigned int cpu, i;
unsigned int prev_chip_id = UINT_MAX;
+ cpumask_t cpu_mask;
+ int ret = -ENOMEM;
- for_each_possible_cpu(cpu) {
+ core_to_chip_map = kcalloc(cpu_nr_cores(), sizeof(unsigned int),
+ GFP_KERNEL);
+ if (!core_to_chip_map)
+ goto out;
+
+ cpumask_copy(&cpu_mask, cpu_possible_mask);
+ for_each_cpu(cpu, &cpu_mask) {
unsigned int id = cpu_to_chip_id(cpu);
if (prev_chip_id != id) {
prev_chip_id = id;
chip[nr_chips++] = id;
}
+ core_to_chip_map[cpu_core_index_of_thread(cpu)] = id;
+ cpumask_andnot(&cpu_mask, &cpu_mask, cpu_sibling_mask(cpu));
}
chips = kmalloc_array(nr_chips, sizeof(struct chip), GFP_KERNEL);
if (!chips)
- return -ENOMEM;
+ goto free_chip_map;
for (i = 0; i < nr_chips; i++) {
chips[i].id = chip[i];
@@ -582,6 +594,10 @@ static int init_chip_info(void)
}
return 0;
+free_chip_map:
+ kfree(core_to_chip_map);
+out:
+ return ret;
}
static int __init powernv_cpufreq_init(void)
@@ -616,6 +632,7 @@ static void __exit powernv_cpufreq_exit(void)
opal_message_notifier_unregister(OPAL_MSG_OCC,
&powernv_cpufreq_opal_nb);
kfree(chips);
+ kfree(core_to_chip_map);
cpufreq_unregister_driver(&powernv_cpufreq_driver);
}
module_exit(powernv_cpufreq_exit);
--
1.9.3
next prev parent reply other threads:[~2016-02-02 19:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 19:41 [PATCH v8 0/6] cpufreq: powernv: Redesign the presentation of throttle notification and solve bug-fixes in the driver Shilpasri G Bhat
2016-02-02 19:41 ` [PATCH v8 1/6] cpufreq: powernv: Free 'chips' on module exit Shilpasri G Bhat
2016-02-02 19:41 ` [PATCH v8 2/6] cpufreq: powernv: Hot-plug safe the kworker thread Shilpasri G Bhat
2016-02-02 19:41 ` Shilpasri G Bhat [this message]
2016-03-18 4:04 ` [PATCH v8 3/6] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path Michael Neuling
2016-03-18 4:11 ` Michael Neuling
2016-03-18 13:13 ` Rafael J. Wysocki
2016-03-18 14:58 ` [PATCH] cpufreq: powernv: Define per_cpu chip pointer to optimize hot-path Shilpasri G Bhat
2016-03-21 7:22 ` Viresh Kumar
2016-03-21 14:13 ` Rafael J. Wysocki
2016-03-18 22:37 ` [PATCH v8 3/6] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path Benjamin Herrenschmidt
2016-03-18 23:20 ` Michael Neuling
2016-02-02 19:41 ` [PATCH v8 4/6] cpufreq: powernv/tracing: Add powernv_throttle tracepoint Shilpasri G Bhat
2016-02-02 19:41 ` [PATCH v8 5/6] cpufreq: powernv: Replace pr_info with trace print for throttle event Shilpasri G Bhat
2016-02-02 19:41 ` [PATCH v8 6/6] cpufreq: powernv: Add sysfs attributes to show throttle stats Shilpasri G Bhat
2016-02-03 8:27 ` Viresh Kumar
2016-02-03 8:42 ` Shilpasri G Bhat
2016-02-03 9:03 ` Viresh Kumar
2016-02-03 12:02 ` Gautham R Shenoy
2016-02-03 14:06 ` Viresh Kumar
2016-02-03 16:24 ` Shilpasri G Bhat
2016-02-04 1:51 ` Viresh Kumar
2016-02-03 13:40 ` [PATCH v8 0/6] cpufreq: powernv: Redesign the presentation of throttle notification and solve bug-fixes in the driver Rafael J. Wysocki
2016-02-03 14:01 ` Viresh Kumar
2016-02-03 16:14 ` Shilpasri G Bhat
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