From: Rusty Russell <rusty@rustcorp•com.au>
To: "netdev" <netdev@vger•kernel.org>
Cc: Jesper Dangaard Brouer <brouer@redhat•com>,
Mathias Krause <minipli@googlemail•com>
Subject: [PATCH] pktgen: nowait parameter.
Date: Wed, 03 Sep 2014 13:50:01 +0930 [thread overview]
Message-ID: <87oauxibda.fsf@rustcorp.com.au> (raw)
While trying to measure speed of virtio_net, I was getting hangs.
This is because we skb_orphan() but delay the tx interrupt
indefinitely (by number of slots).
With nowait, pktgen won't wait for the skb to be released. This
introduces an error, but it's ok if count >> ringsize.
I updated the documentation, but it needs far more work (it
refers to pgset and an examples directory, none of which exist
in the kernel tree).
Signed-off-by: Rusty Russell <rusty@rustcorp•com.au>
diff --git a/Documentation/networking/pktgen.txt b/Documentation/networking/pktgen.txt
index 0dffc6e37902..48d86da74a39 100644
--- a/Documentation/networking/pktgen.txt
+++ b/Documentation/networking/pktgen.txt
@@ -41,10 +41,13 @@ NIC HW layer (which is bad for bufferbloat).
One should be careful to conclude, that packets/descriptors in the HW
TX ring cause delay. Drivers usually delay cleaning up the
ring-buffers (for various performance reasons), thus packets stalling
-the TX ring, might just be waiting for cleanup.
+the TX ring, might just be waiting for cleanup. Writing the "nowait"
+parameter into /proc/net/pktgen/ethX will avoid waiting for cleanup of
+the final packets, introducing a slight error (tiny if the count of
+packets being sent is much greater than the ring size of the device).
-This cleanup issues is specifically the case, for the driver ixgbe
-(Intel 82599 chip). This driver (ixgbe) combine TX+RX ring cleanups,
+Alternately, some drivers (eg ixgbe for the Intel 82599 chip) can
+have their cleanup interval changed. ixgbe combines TX+RX ring cleanups,
and the cleanup interval is affected by the ethtool --coalesce setting
of parameter "rx-usecs".
@@ -303,6 +305,8 @@ flowlen
rate
ratep
+nowait
+
References:
ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/
ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/examples/
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 8b849ddfef2e..adc41f2b3bc7 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -290,6 +290,11 @@ struct pktgen_dev {
* set clone_skb to 1024.
*/
+ bool no_wait; /*
+ * Don't wait for packet to be freed
+ * by driver
+ */
+
char dst_min[IP_NAME_SZ]; /* IP, ie 1.2.3.4 */
char dst_max[IP_NAME_SZ]; /* IP, ie 1.2.3.4 */
char src_min[IP_NAME_SZ]; /* IP, ie 1.2.3.4 */
@@ -679,6 +684,9 @@ static int pktgen_if_show(struct seq_file *seq, void *v)
seq_puts(seq, "\n");
+ if (pkt_dev->no_wait)
+ seq_puts(seq, " nowait\n");
+
/* not really stopped, more like last-running-at */
stopped = pkt_dev->running ? ktime_get() : pkt_dev->stopped_at;
idle = pkt_dev->idle_acc;
@@ -1711,6 +1719,17 @@ static ssize_t pktgen_if_write(struct file *file,
return count;
}
+ if (!strcmp(name, "nowait")) {
+ len = num_arg(&user_buffer[i], 10, &value);
+ if (len < 0)
+ return len;
+
+ i += len;
+ pkt_dev->no_wait = value;
+ sprintf(pg_result, "OK: nowait=%u", pkt_dev->no_wait);
+ return count;
+ }
+
sprintf(pkt_dev->result, "No such parameter \"%s\"", name);
return -EINVAL;
}
@@ -3373,7 +3392,8 @@ unlock:
/* If pkt_dev->count is zero, then run forever */
if ((pkt_dev->count != 0) && (pkt_dev->sofar >= pkt_dev->count)) {
- pktgen_wait_for_skb(pkt_dev);
+ if (!pkt_dev->no_wait)
+ pktgen_wait_for_skb(pkt_dev);
/* Done with this */
pktgen_stop_device(pkt_dev);
@@ -3565,6 +3585,7 @@ static int pktgen_add_device(struct pktgen_thread *t, const char *ifname)
pkt_dev->svlan_cfi = 0;
pkt_dev->svlan_id = 0xffff;
pkt_dev->node = -1;
+ pkt_dev->no_wait = false;
err = pktgen_setup_dev(t->net, pkt_dev, ifname);
if (err)
next reply other threads:[~2014-09-03 4:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-03 4:20 Rusty Russell [this message]
2014-09-03 9:09 ` [PATCH] pktgen: nowait parameter Jesper Dangaard Brouer
2014-09-05 1:49 ` Rusty Russell
2014-09-05 2:52 ` Jason Wang
2014-09-05 21:26 ` David Miller
2014-09-10 23:37 ` Rusty Russell
2014-09-12 21:52 ` David Miller
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