aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc/kernel/time.c
diff options
context:
space:
mode:
authorPaul Mackerras <paulus@samba.org>2009-06-17 21:50:04 +1000
committerIngo Molnar <mingo@elte.hu>2009-06-18 11:11:44 +0200
commit105988c015943e77092a6568bc5fb7e386df6ccd (patch)
treebd352fe5e68a66de2e08a8b91c8f8cccf422f346 /arch/powerpc/kernel/time.c
parenta73c7d84a1975b44c0ebd03c2dec288af1426349 (diff)
perf_counter: powerpc: Enable use of software counters on 32-bit powerpc
This enables the perf_counter subsystem on 32-bit powerpc. Since we don't have any support for hardware counters on 32-bit powerpc yet, only software counters can be used. Besides selecting HAVE_PERF_COUNTERS for 32-bit powerpc as well as 64-bit, the main thing this does is add an implementation of set_perf_counter_pending(). This needs to arrange for perf_counter_do_pending() to be called when interrupts are enabled. Rather than add code to local_irq_restore as 64-bit does, the 32-bit set_perf_counter_pending() generates an interrupt by setting the decrementer to 1 so that a decrementer interrupt will become pending in 1 or 2 timebase ticks (if a decrementer interrupt isn't already pending). When interrupts are enabled, timer_interrupt() will be called, and some new code in there calls perf_counter_do_pending(). We use a per-cpu array of flags to indicate whether we need to call perf_counter_do_pending() or not. This introduces a couple of new Kconfig symbols: PPC_HAVE_PMU_SUPPORT, which is selected by processor families for which we have hardware PMU support (currently only PPC64), and PPC_PERF_CTRS, which enables the powerpc-specific perf_counter back-end. Signed-off-by: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: linuxppc-dev@ozlabs.org Cc: benh@kernel.crashing.org LKML-Reference: <19000.55404.103840.393470@cargo.ozlabs.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/powerpc/kernel/time.c')
-rw-r--r--arch/powerpc/kernel/time.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 15391c2ab01..eae4511ceea 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -53,6 +53,7 @@
#include <linux/posix-timers.h>
#include <linux/irq.h>
#include <linux/delay.h>
+#include <linux/perf_counter.h>
#include <asm/io.h>
#include <asm/processor.h>
@@ -525,6 +526,26 @@ void __init iSeries_time_init_early(void)
}
#endif /* CONFIG_PPC_ISERIES */
+#if defined(CONFIG_PERF_COUNTERS) && defined(CONFIG_PPC32)
+DEFINE_PER_CPU(u8, perf_counter_pending);
+
+void set_perf_counter_pending(void)
+{
+ get_cpu_var(perf_counter_pending) = 1;
+ set_dec(1);
+ put_cpu_var(perf_counter_pending);
+}
+
+#define test_perf_counter_pending() __get_cpu_var(perf_counter_pending)
+#define clear_perf_counter_pending() __get_cpu_var(perf_counter_pending) = 0
+
+#else /* CONFIG_PERF_COUNTERS && CONFIG_PPC32 */
+
+#define test_perf_counter_pending() 0
+#define clear_perf_counter_pending()
+
+#endif /* CONFIG_PERF_COUNTERS && CONFIG_PPC32 */
+
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
@@ -551,6 +572,10 @@ void timer_interrupt(struct pt_regs * regs)
set_dec(DECREMENTER_MAX);
#ifdef CONFIG_PPC32
+ if (test_perf_counter_pending()) {
+ clear_perf_counter_pending();
+ perf_counter_do_pending();
+ }
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);
#endif