On Wednesday 03 June 2015 04:44 AM, Daniel Axtens wrote:
On Tue, 2015-06-02 at 21:29 +0530, Madhavan Srinivasan wrote:
Patch creates a file "nest-pmu-c" to contain nest pmu related functions.
"nest-pmu.c"
Patch adds nest pmu init function and cpumask function since Nest pmu units
are per-chip. First online cpu for a given node is picked as
designated thread to read the counter data.
Subsequent patch adds the hotplug support.
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khand...@linux.vnet.ibm.com>
Cc: Stephane Eranian <eran...@google.com>
Cc: Preeti U Murthy <pre...@linux.vnet.ibm.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Madhavan Srinivasan <ma...@linux.vnet.ibm.com>
---
arch/powerpc/perf/nest-pmu.c | 70 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 70 insertions(+)
create mode 100644 arch/powerpc/perf/nest-pmu.c
diff --git a/arch/powerpc/perf/nest-pmu.c b/arch/powerpc/perf/nest-pmu.c
new file mode 100644
index 0000000..d4413bb
--- /dev/null
+++ b/arch/powerpc/perf/nest-pmu.c
@@ -0,0 +1,70 @@
+/*
+ * Nest Performance Monitor counter support for POWER8 processors.
+ *
+ * Copyright 2015 Madhavan Srinivasan, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
Again, I think this is supposed to be v2 only.
+#include "nest-pmu.h"
+
+static cpumask_t cpu_mask_nest_pmu;
+
+static ssize_t cpumask_nest_pmu_get_attr(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return cpumap_print_to_pagebuf(true, buf, &cpu_mask_nest_pmu);
+}
+
+static DEVICE_ATTR(cpumask, S_IRUGO, cpumask_nest_pmu_get_attr, NULL);
+
+static struct attribute *cpumask_nest_pmu_attrs[] = {
+ &dev_attr_cpumask.attr,
+ NULL,
+};
+
+static struct attribute_group cpumask_nest_pmu_attr_group = {
+ .attrs = cpumask_nest_pmu_attrs,
+};
+
+void cpumask_chip(void)
+{
+ const struct cpumask *l_cpumask;
+ int cpu, nid;
+
+ if (!cpumask_empty(&cpu_mask_nest_pmu)) {
+ printk(KERN_INFO "cpumask not empty\n");
+ return;
+ }
+
+ cpu_notifier_register_begin();
+ for_each_online_node(nid) {
+ l_cpumask = cpumask_of_node(nid);
+ cpu = cpumask_first(l_cpumask);
+ cpumask_set_cpu(cpu, &cpu_mask_nest_pmu);
+ }
+
+ cpu_notifier_register_done();
+}
It's not clear from the name of this function what it does. I don't
think I actually understand what it does: it appears to register a
notifier on the first cpu of each node; maybe that should be reflected
in the name.
My bad. Hotplug notification registration happens in the next patch.
could merge both as single patch.
+static int __init nest_pmu_init(void)
+{
+ int ret = 0;
+
+ /*
+ * Lets do this only if we are hypervisor
+ */
+ if (!cur_cpu_spec->oprofile_cpu_type ||
+ strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power8") ||
+ !cpu_has_feature(CPU_FTR_HVMODE))
+ return ret;
+
+ cpumask_chip();
+
+ return 0;
+}
- Where is ret set? I can only see it set when it's defined: the if
statment doesn't change the value of ret as far as I can see...
Yes. It should have set to error value. Will fix it.
- Would it be clearer if you said
!(strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power8") == 0)
That would make it clearer that you're trying to get a list of
possible failure conditions.
Yes. Sure will change it.
- Is there really no better way to check if a CPU is a power 8 than an
string comparison?
One other way I can think of is using PVR (Processor Version Register),
but then will end up having multiple checks for Power8 itself, so this
is lot simpler.
+device_initcall(nest_pmu_init);
Regards,
Daniel Axtens
Thanks for the review
Maddy
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
