Add Support for Compressible Data Generation

src/common/random.c

@@ -108,6 +108,40 @@ rand_fill(uint8_t* p_buffer, uint32_t size)
 	return true;
 }
 
+//------------------------------------------------
+// Fill a buffer with target compression ratio.
+//
+
+bool
+comp_fill(uint8_t* p_buffer, uint32_t size, uint32_t compress_percent)
+{
+	uint64_t* p_write = (uint64_t*)p_buffer; 	
+	uint64_t* p_end = (uint64_t*)(p_buffer + size);
+	// ... relies on size being a multiple of 8, which it will be.
+	const uint32_t interval_size = 512;   // Space out zero runs at this interval
+	const uint32_t interval_num = size / interval_size;
+	const uint32_t z_len = (((100 - compress_percent) * interval_size) / 100) / sizeof(uint64_t);
+	const uint32_t r_len = (interval_size / sizeof(uint64_t)) - z_len;
+	// ... data must be in interval_size units to achieve target compression ratio
+	int32_t i, z, r;
+
+	for (i = 0; i < interval_num; i++) {
+		z = z_len;
+		while (z--) {
+			*p_write++ = 0;
+		}
+		r = r_len;
+		while (r--) {
+			*p_write++ = xorshift128plus();
+		}
+	}
+
+	while (p_write < p_end) {
+		*p_write++ = xorshift128plus();
+	}
+
+	return true;
+}
 
 //==========================================================
 // Local helpers.

src/common/random.h

@@ -41,3 +41,4 @@ void rand_seed_thread();
 uint32_t rand_32();
 uint64_t rand_64();
 bool rand_fill(uint8_t* p_buffer, uint32_t size);
+bool comp_fill(uint8_t* p_buffer, uint32_t size, uint32_t compress_percent);

src/storage/act_storage.c

@@ -1047,7 +1047,12 @@ static void
 write_and_report(trans_req* write_req, uint8_t* buf)
 {
 	// Salt each record.
-	rand_fill(buf, write_req->size);
+	if (g_scfg.compress_percent < 100) {
+		comp_fill(buf, write_req->size, g_scfg.compress_percent);
+	}
+	else {
+		rand_fill(buf, write_req->size);
+	}
 
 	uint64_t raw_start_time = get_ns();
 	uint64_t stop_time = write_to_device(write_req->dev, write_req->offset,
@@ -1070,7 +1075,12 @@ static void
 write_and_report_large_block(device* dev, uint8_t* buf, uint64_t count)
 {
 	// Salt the block each time.
-	rand_fill(buf, g_scfg.large_block_ops_bytes);
+	if (g_scfg.compress_percent < 100) {
+		comp_fill(buf, g_scfg.large_block_ops_bytes, g_scfg.compress_percent);
+	}
+	else {
+		rand_fill(buf, g_scfg.large_block_ops_bytes);
+	}
 
 	uint64_t offset = random_large_block_offset(dev);
 	uint64_t start_time = get_ns();

src/storage/cfg_storage.c

@@ -69,6 +69,7 @@ static const char TAG_TOMB_RAIDER_SLEEP_USEC[]  = "tomb-raider-sleep-usec";
 static const char TAG_MAX_REQS_QUEUED[]         = "max-reqs-queued";
 static const char TAG_MAX_LAG_SEC[]             = "max-lag-sec";
 static const char TAG_SCHEDULER_MODE[]          = "scheduler-mode";
+static const char TAG_COMPRESS_PERCENT[]        = "compress-percent";
 
 #define RBLOCK_SIZE 16 // must be power of 2
 
@@ -97,7 +98,8 @@ storage_cfg g_scfg = {
 		.defrag_lwm_pct = 50,
 		.max_reqs_queued = 100000,
 		.max_lag_usec = 1000000 * 10,
-		.scheduler_mode = "noop"
+		.scheduler_mode = "noop",
+		.compress_percent = 100
 };
 
 
@@ -226,6 +228,9 @@ storage_configure(int argc, char* argv[])
 		else if (strcmp(tag, TAG_SCHEDULER_MODE) == 0) {
 			g_scfg.scheduler_mode = parse_scheduler_mode();
 		}
+		else if (strcmp(tag, TAG_COMPRESS_PERCENT) == 0) {
+			g_scfg.compress_percent = parse_uint32();
+		}
 		else {
 			fprintf(stdout, "ERROR: ignoring unknown config item '%s'\n", tag);
 		}
@@ -324,6 +329,10 @@ check_configuration()
 		configuration_error(TAG_COMMIT_MIN_BYTES);
 		return false;
 	}
+	if (g_scfg.compress_percent > 100) {
+		configuration_error(TAG_COMPRESS_PERCENT);
+		return false;
+	}
 
 	return true;
 }
@@ -495,6 +504,8 @@ echo_configuration()
 			g_scfg.max_lag_usec / 1000000);
 	fprintf(stdout, "%s: %s\n", TAG_SCHEDULER_MODE,
 			g_scfg.scheduler_mode);
+	fprintf(stdout, "%s: %" PRIu32 "\n", TAG_COMPRESS_PERCENT,
+			g_scfg.compress_percent);
 
 	fprintf(stdout, "\nDERIVED CONFIGURATION\n");
 

src/storage/cfg_storage.h

@@ -76,6 +76,7 @@ typedef struct storage_cfg_s {
 	uint32_t write_req_threads;
 	double large_block_reads_per_sec;
 	double large_block_writes_per_sec;
+	uint32_t compress_percent;
 } storage_cfg;