From: Karl Palsson <karlp@tweak.net.au>
Date: Fri, 8 Sep 2017 15:44:52 +0000 (+0000)
Subject: profiling: write "correct" sample rate to gmon output
X-Git-Tag: v0.11.0-rc1~1271
X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=commitdiff_plain;h=9cd74c113c3a92dd41485ad4d9ba0a275682712b

profiling: write "correct" sample rate to gmon output

This duration vs sample count is _significantly_ closer to the truth
than simply declaring the value to be 100Hz.

Change-Id: Ie8d8bdf1959e1aa7cead0631cd2c86afe77d1efc
Signed-off-by: Karl Palsson <karlp@tweak.net.au>
Reviewed-on: http://openocd.zylin.com/4221
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
---

diff --git a/src/target/target.c b/src/target/target.c
index a9907b0c3e..d6781a3c4e 100644
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -3838,7 +3838,7 @@ typedef unsigned char UNIT[2];  /* unit of profiling */
 
 /* Dump a gmon.out histogram file. */
 static void write_gmon(uint32_t *samples, uint32_t sampleNum, const char *filename, bool with_range,
-			uint32_t start_address, uint32_t end_address, struct target *target)
+			uint32_t start_address, uint32_t end_address, struct target *target, uint32_t duration_ms)
 {
 	uint32_t i;
 	FILE *f = fopen(filename, "w");
@@ -3906,7 +3906,8 @@ static void write_gmon(uint32_t *samples, uint32_t sampleNum, const char *filena
 	writeLong(f, min, target);			/* low_pc */
 	writeLong(f, max, target);			/* high_pc */
 	writeLong(f, numBuckets, target);	/* # of buckets */
-	writeLong(f, 100, target);			/* KLUDGE! We lie, ca. 100Hz best case. */
+	float sample_rate = sampleNum / (duration_ms / 1000.0);
+	writeLong(f, sample_rate, target);
 	writeString(f, "seconds");
 	for (i = 0; i < (15-strlen("seconds")); i++)
 		writeData(f, &zero, 1);
@@ -3955,6 +3956,7 @@ COMMAND_HANDLER(handle_profile_command)
 		return ERROR_FAIL;
 	}
 
+	uint64_t timestart_ms = timeval_ms();
 	/**
 	 * Some cores let us sample the PC without the
 	 * annoying halt/resume step; for example, ARMv7 PCSR.
@@ -3966,6 +3968,7 @@ COMMAND_HANDLER(handle_profile_command)
 		free(samples);
 		return retval;
 	}
+	uint32_t duration_ms = timeval_ms() - timestart_ms;
 
 	assert(num_of_samples <= MAX_PROFILE_SAMPLE_NUM);
 
@@ -3998,7 +4001,7 @@ COMMAND_HANDLER(handle_profile_command)
 	}
 
 	write_gmon(samples, num_of_samples, CMD_ARGV[1],
-		   with_range, start_address, end_address, target);
+		   with_range, start_address, end_address, target, duration_ms);
 	command_print(CMD_CTX, "Wrote %s", CMD_ARGV[1]);
 
 	free(samples);