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Date: Sat, 29 May 2010 22:24:09 +0400
From: Cyrill Gorcunov <gorcunov@...il.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
Frédéric Weisbecker <fweisbec@...il.com>,
Robert Richter <robert.richter@....com>,
Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: [RFC] perf, x86: Segregate PMU workaraunds into x86_pmu_quirk_ops
structure
Hi,
I would appreciate comments/complains on the following patch. The idea is to implement
PMU quirks with minimal impact. At the moment two quirks are addressed -
PEBS disabling on Clovertown and P4 performance counter double write.
PEBS disabling already was there only moved to x86_pmu_quirk_ops. Note
that I didn't use pointer to the structure intensionally but embed it into
x86_pmu, if the structure grow we will need to use a pointer to the structure.
Comments, complains please? Perhaps there is some idea which allow
to handle this all more gentle?
-- Cyrill
---
perf, x86: Segregate PMU workaraunds into x86_pmu_quirk_ops structure
This allow us to handle both Clovertown and Netburst quirks in
a general fashion.
Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
---
arch/x86/kernel/cpu/perf_event.c | 18 ++++++++--
arch/x86/kernel/cpu/perf_event_intel.c | 55 ++++++++++++++++++---------------
arch/x86/kernel/cpu/perf_event_p4.c | 21 ++++++++++++
3 files changed, 64 insertions(+), 30 deletions(-)
Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event.c
+++ linux-2.6.git/arch/x86/kernel/cpu/perf_event.c
@@ -185,6 +185,11 @@ union perf_capabilities {
u64 capabilities;
};
+struct x86_pmu_quirk_ops {
+ void (*pmu_init)(void);
+ void (*perfctr_write)(unsigned long addr, u64 value);
+};
+
/*
* struct x86_pmu - generic x86 pmu
*/
@@ -218,7 +223,8 @@ struct x86_pmu {
void (*put_event_constraints)(struct cpu_hw_events *cpuc,
struct perf_event *event);
struct event_constraint *event_constraints;
- void (*quirks)(void);
+
+ struct x86_pmu_quirk_ops quirks;
int (*cpu_prepare)(int cpu);
void (*cpu_starting)(int cpu);
@@ -924,7 +930,11 @@ x86_perf_event_set_period(struct perf_ev
*/
atomic64_set(&hwc->prev_count, (u64)-left);
- wrmsrl(hwc->event_base + idx,
+ if (x86_pmu.quirks.perfctr_write)
+ x86_pmu.quirks.perfctr_write(hwc->event_base + idx,
+ (u64)(-left) & x86_pmu.cntval_mask);
+ else
+ wrmsrl(hwc->event_base + idx,
(u64)(-left) & x86_pmu.cntval_mask);
perf_event_update_userpage(event);
@@ -1316,8 +1326,8 @@ void __init init_hw_perf_events(void)
pr_cont("%s PMU driver.\n", x86_pmu.name);
- if (x86_pmu.quirks)
- x86_pmu.quirks();
+ if (x86_pmu.quirks.pmu_init)
+ x86_pmu.quirks.pmu_init();
if (x86_pmu.num_counters > X86_PMC_MAX_GENERIC) {
WARN(1, KERN_ERR "hw perf events %d > max(%d), clipping!",
Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_intel.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_intel.c
+++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_intel.c
@@ -822,6 +822,36 @@ static void intel_pmu_cpu_dying(int cpu)
fini_debug_store_on_cpu(cpu);
}
+static void intel_clovertown_pmu_init(void)
+{
+ /*
+ * PEBS is unreliable due to:
+ *
+ * AJ67 - PEBS may experience CPL leaks
+ * AJ68 - PEBS PMI may be delayed by one event
+ * AJ69 - GLOBAL_STATUS[62] will only be set when DEBUGCTL[12]
+ * AJ106 - FREEZE_LBRS_ON_PMI doesn't work in combination with PEBS
+ *
+ * AJ67 could be worked around by restricting the OS/USR flags.
+ * AJ69 could be worked around by setting PMU_FREEZE_ON_PMI.
+ *
+ * AJ106 could possibly be worked around by not allowing LBR
+ * usage from PEBS, including the fixup.
+ * AJ68 could possibly be worked around by always programming
+ * a pebs_event_reset[0] value and coping with the lost events.
+ *
+ * But taken together it might just make sense to not enable PEBS on
+ * these chips.
+ */
+ printk(KERN_WARNING "PEBS disabled due to CPU errata.\n");
+ x86_pmu.pebs = 0;
+ x86_pmu.pebs_constraints = NULL;
+}
+
+static __initconst const struct x86_pmu_quirk_ops intel_clovertown_quirks = {
+ .pmu_init = intel_clovertown_pmu_init,
+};
+
static __initconst const struct x86_pmu intel_pmu = {
.name = "Intel",
.handle_irq = intel_pmu_handle_irq,
@@ -848,31 +878,6 @@ static __initconst const struct x86_pmu
.cpu_dying = intel_pmu_cpu_dying,
};
-static void intel_clovertown_quirks(void)
-{
- /*
- * PEBS is unreliable due to:
- *
- * AJ67 - PEBS may experience CPL leaks
- * AJ68 - PEBS PMI may be delayed by one event
- * AJ69 - GLOBAL_STATUS[62] will only be set when DEBUGCTL[12]
- * AJ106 - FREEZE_LBRS_ON_PMI doesn't work in combination with PEBS
- *
- * AJ67 could be worked around by restricting the OS/USR flags.
- * AJ69 could be worked around by setting PMU_FREEZE_ON_PMI.
- *
- * AJ106 could possibly be worked around by not allowing LBR
- * usage from PEBS, including the fixup.
- * AJ68 could possibly be worked around by always programming
- * a pebs_event_reset[0] value and coping with the lost events.
- *
- * But taken together it might just make sense to not enable PEBS on
- * these chips.
- */
- printk(KERN_WARNING "PEBS disabled due to CPU errata.\n");
- x86_pmu.pebs = 0;
- x86_pmu.pebs_constraints = NULL;
-}
static __init int intel_pmu_init(void)
{
Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_p4.c
+++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
@@ -804,6 +804,24 @@ done:
return num ? -ENOSPC : 0;
}
+/*
+ * This handles errata N15 in intel doc 249199-029,
+ * the counter may not be updated correctly on write
+ * so we repeat write operation twice to do the trick
+ * (the official workaround didn't work)
+ *
+ * the former idea is taken from OProfile code
+ */
+static void p4_perfctr_write(unsigned long addr, u64 value)
+{
+ wrmsrl(addr, value);
+ wrmsrl(addr, value);
+}
+
+static __initconst const struct x86_pmu_quirk_ops p4_pmu_quirks = {
+ .perfctr_write = p4_perfctr_write,
+};
+
static __initconst const struct x86_pmu p4_pmu = {
.name = "Netburst P4/Xeon",
.handle_irq = p4_pmu_handle_irq,
@@ -850,7 +868,8 @@ static __init int p4_pmu_init(void)
pr_cont("Netburst events, ");
- x86_pmu = p4_pmu;
+ x86_pmu = p4_pmu;
+ x86_pmu.quirks = p4_pmu_quirks;
return 0;
}
--
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