pktgen: increasing transmission granularity

This patch increases the granularity of the rate generated by pktgen. The previous version of pktgen uses micro seconds (udelay) resolution when it was delayed causing gaps in the rates. It is changed to nanosecond (ndelay). Now any rate is possible.

Also it allows to set, the desired rate in Mb/s or packets per second.

The documentation has been updated.

Signed-off-by Daniel Turull <[email protected]>

Daniel Turull wrote: This patch correct a bug in the delay of pktgen. It makes sure the inter-packet interval is accurate.

Signed-off-by Daniel Turull <[email protected]>

---

net/core/pktgen.c index renamed from net/core/pktgen.c +0 -0

2ad68da..1dacd7b 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -2170,7 +2170,7 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until)

	end_time = ktime_now();

	pkt_dev->idle_acc += ktime_to_ns(ktime_sub(end_time,

start_time));

net/core/pktgen.c index renamed from net/core/pktgen.c +1 -1

-	pkt_dev->next_tx = ktime_add_ns(end_time, pkt_dev->delay);
+	pkt_dev->next_tx = ktime_add_ns(spin_until, pkt_dev->delay);

}

static inline void set_pkt_overhead(struct pktgen_dev *pkt_dev)

So the scheduling of the next transmission is based on the previous transmission rather rather than now() + delay.

Signed-off-by Robert Olsson <[email protected]>

Quoted 4 lines

Daniel Turull wrote: This patch correct a bug in the delay of pktgen. It makes sure the inter-packet interval is accurate.

Signed-off-by Daniel Turull <[email protected]>

This patch increases the granularity of the rate generated by pktgen. The previous version of pktgen uses micro seconds (udelay) resolution when it was delayed causing gaps in the rates. It is changed to nanosecond (ndelay). Now any rate is possible.

Also it allows to set, the desired rate in Mb/s or packets per second.

The documentation has been updated.

Signed-off-by Daniel Turull <[email protected]>

---

Documentation/networking/pktgen.txt +5 -0

index 61bb645..75e4fd7 100644
@@ -151,6 +151,8 @@ Examples:
 
  pgset stop    	          aborts injection. Also, ^C aborts generator.
 
+ pgset "rate 300M"        set rate to 300 Mb/s
+ pgset "ratep 1000000"    set rate to 1Mpps
 
 Example scripts
 ===============

@@ -241,6 +243,9 @@ src6
 flows
 flowlen
 
+rate
+ratep
+
 References:
 ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/
 ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/examples/

net/core/pktgen.c +38 -4

index 1dacd7b..6428653 100644
@@ -169,7 +169,7 @@
 #include <asm/dma.h>
 #include <asm/div64.h>		/* do_div */
 
-#define VERSION 	"2.73"
+#define VERSION	"2.74"
 #define IP_NAME_SZ 32
 #define MAX_MPLS_LABELS 16 /* This is the max label stack depth */
 #define MPLS_STACK_BOTTOM htonl(0x00000100)

@@ -980,6 +980,40 @@ static ssize_t pktgen_if_write(struct file *file,
 			(unsigned long long) pkt_dev->delay);
 		return count;
 	}
+	if (!strcmp(name, "rate")) {
+		len = num_arg(&user_buffer[i], 10, &value);
+		if (len < 0)
+			return len;
+
+		i += len;
+		if (!value)
+			return len;
+		pkt_dev->delay = pkt_dev->min_pkt_size*8*NSEC_PER_USEC/value;
+		if (debug)
+			printk(KERN_INFO
+				 "pktgen: Delay set at: %llu ns\n",
+					pkt_dev->delay);
+
+		sprintf(pg_result, "OK: rate=%lu", value);
+		return count;
+	}
+	if (!strcmp(name, "ratep")) {
+		len = num_arg(&user_buffer[i], 10, &value);
+		if (len < 0)
+			return len;
+
+		i += len;
+		if (!value)
+			return len;
+		pkt_dev->delay = NSEC_PER_SEC/value;
+		if (debug)
+			printk(KERN_INFO
+				 "pktgen: Delay set at: %llu ns\n",
+					pkt_dev->delay);
+
+		sprintf(pg_result, "OK: rate=%lu", value);
+		return count;
+	}
 	if (!strcmp(name, "udp_src_min")) {
 		len = num_arg(&user_buffer[i], 10, &value);
 		if (len < 0)

@@ -2142,15 +2176,15 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until)
 	hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 	hrtimer_set_expires(&t.timer, spin_until);
 
-	remaining = ktime_to_us(hrtimer_expires_remaining(&t.timer));
+	remaining = ktime_to_ns(hrtimer_expires_remaining(&t.timer));
 	if (remaining <= 0) {
 		pkt_dev->next_tx = ktime_add_ns(spin_until, pkt_dev->delay);
 		return;
 	}
 
 	start_time = ktime_now();
-	if (remaining < 100)
-		udelay(remaining); 	/* really small just spin */
+	if (remaining < 100000)
+		ndelay(remaining);	/* really small just spin */
 	else {
 		/* see do_nanosleep */
 		hrtimer_init_sleeper(&t, current);

So with this improved rate control we could do RFC2544-like testing as well.

Signed-off-by Robert Olsson <[email protected]>