From: Anton Blanchard <anton@samba.org>
To: Steven Rostedt <rostedt@goodmis.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
benh@kernel.crashing.org
Cc: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 3/6] powerpc: tracing: Add hypervisor call tracepoints
Date: Tue, 27 Oct 2009 15:50:29 +1100 [thread overview]
Message-ID: <20091027045029.GD3085@kryten> (raw)
In-Reply-To: <20091027044914.GC3085@kryten>
Add hcall_entry and hcall_exit tracepoints. This replaces the inline
assembly HCALL_STATS code and converts it to use the new tracepoints.
To keep the disabled case as quick as possible, we embed a status word
in the TOC so we can get at it with a single load. By doing so we
keep the overhead at a minimum. Time taken for a null hcall:
No tracepoint code: 135.79 cycles
Disabled tracepoints: 137.95 cycles
For reference, before this patch enabling HCALL_STATS resulted in a null
hcall of 201.44 cycles!
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: linux.trees.git/arch/powerpc/platforms/pseries/hvCall.S
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/hvCall.S 2009-10-27 13:36:05.000000000 +1100
+++ linux.trees.git/arch/powerpc/platforms/pseries/hvCall.S 2009-10-27 14:53:21.000000000 +1100
@@ -14,20 +14,54 @@
#define STK_PARM(i) (48 + ((i)-3)*8)
-#ifdef CONFIG_HCALL_STATS
+#ifdef CONFIG_TRACEPOINTS
+
+ .section ".toc","aw"
+
+ .globl hcall_tracepoint_refcount
+hcall_tracepoint_refcount:
+ .llong 0
+
+ .section ".text"
+
/*
* precall must preserve all registers. use unused STK_PARM()
- * areas to save snapshots and opcode.
+ * areas to save snapshots and opcode. We branch around this
+ * in early init (eg when populating the MMU hashtable) by using an
+ * unconditional cpu feature.
*/
#define HCALL_INST_PRECALL \
- std r3,STK_PARM(r3)(r1); /* save opcode */ \
- mftb r0; /* get timebase and */ \
- std r0,STK_PARM(r5)(r1); /* save for later */ \
BEGIN_FTR_SECTION; \
- mfspr r0,SPRN_PURR; /* get PURR and */ \
- std r0,STK_PARM(r6)(r1); /* save for later */ \
-END_FTR_SECTION_IFSET(CPU_FTR_PURR);
-
+ b 1f; \
+END_FTR_SECTION(0, 1); \
+ ld r12,hcall_tracepoint_refcount@toc(r2); \
+ cmpdi r12,0; \
+ beq+ 1f; \
+ mflr r0; \
+ std r3,STK_PARM(r3)(r1); \
+ std r4,STK_PARM(r4)(r1); \
+ std r5,STK_PARM(r5)(r1); \
+ std r6,STK_PARM(r6)(r1); \
+ std r7,STK_PARM(r7)(r1); \
+ std r8,STK_PARM(r8)(r1); \
+ std r9,STK_PARM(r9)(r1); \
+ std r10,STK_PARM(r10)(r1); \
+ std r0,16(r1); \
+ stdu r1,-STACK_FRAME_OVERHEAD(r1); \
+ bl .__trace_hcall_entry; \
+ addi r1,r1,STACK_FRAME_OVERHEAD; \
+ ld r0,16(r1); \
+ ld r3,STK_PARM(r3)(r1); \
+ ld r4,STK_PARM(r4)(r1); \
+ ld r5,STK_PARM(r5)(r1); \
+ ld r6,STK_PARM(r6)(r1); \
+ ld r7,STK_PARM(r7)(r1); \
+ ld r8,STK_PARM(r8)(r1); \
+ ld r9,STK_PARM(r9)(r1); \
+ ld r10,STK_PARM(r10)(r1); \
+ mtlr r0; \
+1:
+
/*
* postcall is performed immediately before function return which
* allows liberal use of volatile registers. We branch around this
@@ -38,40 +72,21 @@ END_FTR_SECTION_IFSET(CPU_FTR_PURR);
BEGIN_FTR_SECTION; \
b 1f; \
END_FTR_SECTION(0, 1); \
- ld r4,STK_PARM(r3)(r1); /* validate opcode */ \
- cmpldi cr7,r4,MAX_HCALL_OPCODE; \
- bgt- cr7,1f; \
- \
- /* get time and PURR snapshots after hcall */ \
- mftb r7; /* timebase after */ \
-BEGIN_FTR_SECTION; \
- mfspr r8,SPRN_PURR; /* PURR after */ \
- ld r6,STK_PARM(r6)(r1); /* PURR before */ \
- subf r6,r6,r8; /* delta */ \
-END_FTR_SECTION_IFSET(CPU_FTR_PURR); \
- ld r5,STK_PARM(r5)(r1); /* timebase before */ \
- subf r5,r5,r7; /* time delta */ \
- \
- /* calculate address of stat structure r4 = opcode */ \
- srdi r4,r4,2; /* index into array */ \
- mulli r4,r4,HCALL_STAT_SIZE; \
- LOAD_REG_ADDR(r7, per_cpu__hcall_stats); \
- add r4,r4,r7; \
- ld r7,PACA_DATA_OFFSET(r13); /* per cpu offset */ \
- add r4,r4,r7; \
- \
- /* update stats */ \
- ld r7,HCALL_STAT_CALLS(r4); /* count */ \
- addi r7,r7,1; \
- std r7,HCALL_STAT_CALLS(r4); \
- ld r7,HCALL_STAT_TB(r4); /* timebase */ \
- add r7,r7,r5; \
- std r7,HCALL_STAT_TB(r4); \
-BEGIN_FTR_SECTION; \
- ld r7,HCALL_STAT_PURR(r4); /* PURR */ \
- add r7,r7,r6; \
- std r7,HCALL_STAT_PURR(r4); \
-END_FTR_SECTION_IFSET(CPU_FTR_PURR); \
+ ld r12,hcall_tracepoint_refcount@toc(r2); \
+ cmpdi r12,0; \
+ beq+ 1f; \
+ mflr r0; \
+ ld r6,STK_PARM(r3)(r1); \
+ std r3,STK_PARM(r3)(r1); \
+ mr r4,r3; \
+ mr r3,r6; \
+ std r0,16(r1); \
+ stdu r1,-STACK_FRAME_OVERHEAD(r1); \
+ bl .__trace_hcall_exit; \
+ addi r1,r1,STACK_FRAME_OVERHEAD; \
+ ld r0,16(r1); \
+ ld r3,STK_PARM(r3)(r1); \
+ mtlr r0; \
1:
#else
#define HCALL_INST_PRECALL
Index: linux.trees.git/arch/powerpc/platforms/pseries/lpar.c
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/lpar.c 2009-10-27 13:36:05.000000000 +1100
+++ linux.trees.git/arch/powerpc/platforms/pseries/lpar.c 2009-10-27 14:53:21.000000000 +1100
@@ -39,6 +39,7 @@
#include <asm/cputable.h>
#include <asm/udbg.h>
#include <asm/smp.h>
+#include <asm/trace.h>
#include "plpar_wrappers.h"
#include "pseries.h"
@@ -661,3 +662,34 @@ void arch_free_page(struct page *page, i
EXPORT_SYMBOL(arch_free_page);
#endif
+
+#ifdef CONFIG_TRACEPOINTS
+/*
+ * We optimise our hcall path by placing hcall_tracepoint_refcount
+ * directly in the TOC so we can check if the hcall tracepoints are
+ * enabled via a single load.
+ */
+
+/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
+extern long hcall_tracepoint_refcount;
+
+void hcall_tracepoint_regfunc(void)
+{
+ hcall_tracepoint_refcount++;
+}
+
+void hcall_tracepoint_unregfunc(void)
+{
+ hcall_tracepoint_refcount--;
+}
+
+void __trace_hcall_entry(unsigned long opcode)
+{
+ trace_hcall_entry(opcode);
+}
+
+void __trace_hcall_exit(long opcode, unsigned long retval)
+{
+ trace_hcall_exit(opcode, retval);
+}
+#endif
Index: linux.trees.git/arch/powerpc/include/asm/trace.h
===================================================================
--- linux.trees.git.orig/arch/powerpc/include/asm/trace.h 2009-10-27 13:36:30.000000000 +1100
+++ linux.trees.git/arch/powerpc/include/asm/trace.h 2009-10-27 14:56:38.000000000 +1100
@@ -76,6 +76,51 @@ TRACE_EVENT(timer_interrupt_exit,
TP_printk("pt_regs=%p", __entry->regs)
);
+#ifdef CONFIG_PPC_PSERIES
+extern void hcall_tracepoint_regfunc(void);
+extern void hcall_tracepoint_unregfunc(void);
+
+TRACE_EVENT_FN(hcall_entry,
+
+ TP_PROTO(unsigned long opcode),
+
+ TP_ARGS(opcode),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, opcode)
+ ),
+
+ TP_fast_assign(
+ __entry->opcode = opcode;
+ ),
+
+ TP_printk("opcode=%lu", __entry->opcode),
+
+ hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc
+);
+
+TRACE_EVENT_FN(hcall_exit,
+
+ TP_PROTO(unsigned long opcode, unsigned long retval),
+
+ TP_ARGS(opcode, retval),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, opcode)
+ __field(unsigned long, retval)
+ ),
+
+ TP_fast_assign(
+ __entry->opcode = opcode;
+ __entry->retval = retval;
+ ),
+
+ TP_printk("opcode=%lu retval=%lu", __entry->opcode, __entry->retval),
+
+ hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc
+);
+#endif
+
#endif /* _TRACE_POWERPC_H */
#undef TRACE_INCLUDE_PATH
Index: linux.trees.git/arch/powerpc/include/asm/hvcall.h
===================================================================
--- linux.trees.git.orig/arch/powerpc/include/asm/hvcall.h 2009-10-27 13:36:05.000000000 +1100
+++ linux.trees.git/arch/powerpc/include/asm/hvcall.h 2009-10-27 14:53:21.000000000 +1100
@@ -274,6 +274,8 @@ struct hcall_stats {
unsigned long num_calls; /* number of calls (on this CPU) */
unsigned long tb_total; /* total wall time (mftb) of calls. */
unsigned long purr_total; /* total cpu time (PURR) of calls. */
+ unsigned long tb_start;
+ unsigned long purr_start;
};
#define HCALL_STAT_ARRAY_SIZE ((MAX_HCALL_OPCODE >> 2) + 1)
Index: linux.trees.git/arch/powerpc/platforms/pseries/hvCall_inst.c
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/hvCall_inst.c 2009-10-27 13:36:05.000000000 +1100
+++ linux.trees.git/arch/powerpc/platforms/pseries/hvCall_inst.c 2009-10-27 14:53:21.000000000 +1100
@@ -26,6 +26,7 @@
#include <asm/hvcall.h>
#include <asm/firmware.h>
#include <asm/cputable.h>
+#include <asm/trace.h>
DEFINE_PER_CPU(struct hcall_stats[HCALL_STAT_ARRAY_SIZE], hcall_stats);
@@ -100,6 +101,34 @@ static const struct file_operations hcal
#define HCALL_ROOT_DIR "hcall_inst"
#define CPU_NAME_BUF_SIZE 32
+
+static void probe_hcall_entry(unsigned long opcode)
+{
+ struct hcall_stats *h;
+
+ if (opcode > MAX_HCALL_OPCODE)
+ return;
+
+ h = &get_cpu_var(hcall_stats)[opcode / 4];
+ h->tb_start = mftb();
+ h->purr_start = mfspr(SPRN_PURR);
+}
+
+static void probe_hcall_exit(unsigned long opcode, unsigned long retval)
+{
+ struct hcall_stats *h;
+
+ if (opcode > MAX_HCALL_OPCODE)
+ return;
+
+ h = &__get_cpu_var(hcall_stats)[opcode / 4];
+ h->num_calls++;
+ h->tb_total = mftb() - h->tb_start;
+ h->purr_total = mfspr(SPRN_PURR) - h->purr_start;
+
+ put_cpu_var(hcall_stats);
+}
+
static int __init hcall_inst_init(void)
{
struct dentry *hcall_root;
@@ -110,6 +139,14 @@ static int __init hcall_inst_init(void)
if (!firmware_has_feature(FW_FEATURE_LPAR))
return 0;
+ if (register_trace_hcall_entry(probe_hcall_entry))
+ return -EINVAL;
+
+ if (register_trace_hcall_exit(probe_hcall_exit)) {
+ unregister_trace_hcall_entry(probe_hcall_entry);
+ return -EINVAL;
+ }
+
hcall_root = debugfs_create_dir(HCALL_ROOT_DIR, NULL);
if (!hcall_root)
return -ENOMEM;
Index: linux.trees.git/arch/powerpc/Kconfig.debug
===================================================================
--- linux.trees.git.orig/arch/powerpc/Kconfig.debug 2009-10-27 13:36:05.000000000 +1100
+++ linux.trees.git/arch/powerpc/Kconfig.debug 2009-10-27 13:36:30.000000000 +1100
@@ -46,7 +46,7 @@ config DEBUG_STACK_USAGE
config HCALL_STATS
bool "Hypervisor call instrumentation"
- depends on PPC_PSERIES && DEBUG_FS
+ depends on PPC_PSERIES && DEBUG_FS && TRACEPOINTS
help
Adds code to keep track of the number of hypervisor calls made and
the amount of time spent in hypervisor calls. Wall time spent in
next prev parent reply other threads:[~2009-10-27 4:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-27 4:47 [PATCH 1/6] powerpc: tracing: Add powerpc tracepoints for interrupt entry and exit Anton Blanchard
2009-10-27 4:49 ` [PATCH 2/6] powerpc: tracing: Add powerpc tracepoints for timer " Anton Blanchard
2009-10-27 4:50 ` Anton Blanchard [this message]
2009-10-27 4:51 ` [PATCH 4/6] powerpc: tracing: Give hypervisor call tracepoints access to arguments Anton Blanchard
2009-10-27 4:51 ` [PATCH 5/6] powerpc: Disable HCALL_STATS by default Anton Blanchard
2009-10-27 4:52 ` [PATCH 6/6] powerpc: Export powerpc_debugfs_root Anton Blanchard
2009-10-27 5:02 ` hypervisor call trace module Anton Blanchard
2009-10-27 22:00 ` [PATCH 1/6] powerpc: tracing: Add powerpc tracepoints for interrupt entry and exit Steven Rostedt
2009-10-27 23:41 ` Benjamin Herrenschmidt
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