[PATCH v3] ARM: kprobes: Add some benchmarking to test module
Tixy
tixy at yxit.co.uk
Sun Sep 18 07:17:58 EDT 2011
From: Jon Medhurst <tixy at yxit.co.uk>
These benchmarks show the basic speed of kprobes and verify the success
of optimisations done to the emulation of typical function entry
instructions (i.e. push/stmdb).
Signed-off-by: Jon Medhurst <tixy at yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre at linaro.org>
---
Changes since v2:
- Modify benchmark() to use sched_clock() rather than do_gettimeofday()
as this has lower overheads and gives simpler code - as suggested by
Nicolas Pitre.
---
arch/arm/kernel/kprobes-test.c | 161 ++++++++++++++++++++++++++++++++++++++++
1 files changed, 161 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/kprobes-test.c b/arch/arm/kernel/kprobes-test.c
index fe169e9..e5740c7 100644
--- a/arch/arm/kernel/kprobes-test.c
+++ b/arch/arm/kernel/kprobes-test.c
@@ -185,6 +185,9 @@
#include "kprobes-test.h"
+#define BENCHMARKING 1
+
+
/*
* Test basic API
*/
@@ -444,6 +447,157 @@ static int run_api_tests(long (*func)(long, long))
/*
+ * Benchmarking
+ */
+
+#if BENCHMARKING
+
+static void __naked benchmark_nop(void)
+{
+ __asm__ __volatile__ (
+ "nop \n\t"
+ "bx lr"
+ );
+}
+
+#ifdef CONFIG_THUMB2_KERNEL
+#define wide ".w"
+#else
+#define wide
+#endif
+
+static void __naked benchmark_pushpop1(void)
+{
+ __asm__ __volatile__ (
+ "stmdb"wide" sp!, {r3-r11,lr} \n\t"
+ "ldmia"wide" sp!, {r3-r11,pc}"
+ );
+}
+
+static void __naked benchmark_pushpop2(void)
+{
+ __asm__ __volatile__ (
+ "stmdb"wide" sp!, {r0-r8,lr} \n\t"
+ "ldmia"wide" sp!, {r0-r8,pc}"
+ );
+}
+
+static void __naked benchmark_pushpop3(void)
+{
+ __asm__ __volatile__ (
+ "stmdb"wide" sp!, {r4,lr} \n\t"
+ "ldmia"wide" sp!, {r4,pc}"
+ );
+}
+
+static void __naked benchmark_pushpop4(void)
+{
+ __asm__ __volatile__ (
+ "stmdb"wide" sp!, {r0,lr} \n\t"
+ "ldmia"wide" sp!, {r0,pc}"
+ );
+}
+
+
+#ifdef CONFIG_THUMB2_KERNEL
+
+static void __naked benchmark_pushpop_thumb(void)
+{
+ __asm__ __volatile__ (
+ "push.n {r0-r7,lr} \n\t"
+ "pop.n {r0-r7,pc}"
+ );
+}
+
+#endif
+
+static int __kprobes
+benchmark_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ return 0;
+}
+
+static int benchmark(void(*fn)(void))
+{
+ unsigned n, i, t, t0;
+
+ for (n = 1000; ; n *= 2) {
+ t0 = sched_clock();
+ for (i = n; i > 0; --i)
+ fn();
+ t = sched_clock() - t0;
+ if (t >= 250000000)
+ break; /* Stop once we took more than 0.25 seconds */
+ }
+ return t / n; /* Time for one iteration in nanoseconds */
+};
+
+static int kprobe_benchmark(void(*fn)(void), unsigned offset)
+{
+ struct kprobe k = {
+ .addr = (kprobe_opcode_t *)((uintptr_t)fn + offset),
+ .pre_handler = benchmark_pre_handler,
+ };
+
+ int ret = register_kprobe(&k);
+ if (ret < 0) {
+ pr_err("FAIL: register_kprobe failed with %d\n", ret);
+ return ret;
+ }
+
+ ret = benchmark(fn);
+
+ unregister_kprobe(&k);
+ return ret;
+};
+
+struct benchmarks {
+ void (*fn)(void);
+ unsigned offset;
+ const char *title;
+};
+
+static int run_benchmarks(void)
+{
+ int ret;
+ struct benchmarks list[] = {
+ {&benchmark_nop, 0, "nop"},
+ /*
+ * benchmark_pushpop{1,3} will have the optimised
+ * instruction emulation, whilst benchmark_pushpop{2,4} will
+ * be the equivalent unoptimised instructions.
+ */
+ {&benchmark_pushpop1, 0, "stmdb sp!, {r3-r11,lr}"},
+ {&benchmark_pushpop1, 4, "ldmia sp!, {r3-r11,pc}"},
+ {&benchmark_pushpop2, 0, "stmdb sp!, {r0-r8,lr}"},
+ {&benchmark_pushpop2, 4, "ldmia sp!, {r0-r8,pc}"},
+ {&benchmark_pushpop3, 0, "stmdb sp!, {r4,lr}"},
+ {&benchmark_pushpop3, 4, "ldmia sp!, {r4,pc}"},
+ {&benchmark_pushpop4, 0, "stmdb sp!, {r0,lr}"},
+ {&benchmark_pushpop4, 4, "ldmia sp!, {r0,pc}"},
+#ifdef CONFIG_THUMB2_KERNEL
+ {&benchmark_pushpop_thumb, 0, "push.n {r0-r7,lr}"},
+ {&benchmark_pushpop_thumb, 2, "pop.n {r0-r7,pc}"},
+#endif
+ {0}
+ };
+
+ struct benchmarks *b;
+ for (b = list; b->fn; ++b) {
+ ret = kprobe_benchmark(b->fn, b->offset);
+ if (ret < 0)
+ return ret;
+ pr_info(" %dns for kprobe %s\n", ret, b->title);
+ }
+
+ pr_info("\n");
+ return 0;
+}
+
+#endif /* BENCHMARKING */
+
+
+/*
* Decoding table self-consistency tests
*/
@@ -1526,6 +1680,13 @@ static int __init run_all_tests(void)
goto out;
}
+#if BENCHMARKING
+ pr_info("Benchmarks\n");
+ ret = run_benchmarks();
+ if (ret)
+ goto out;
+#endif
+
#if __LINUX_ARM_ARCH__ >= 7
/* We are able to run all test cases so coverage should be complete */
if (coverage_fail) {
--
1.7.2.5
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