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| author | Jesper Dangaard Brouer <brouer@redhat.com> | 2014-06-26 13:16:49 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-07-01 15:50:23 -0700 |
| commit | baac167b706600ebe7158acaeb7c489ae9d0bb8b (patch) | |
| tree | e7fe4f63eb410252d15ef5536e97a4adc08fc881 | |
| parent | 9ceb87fceacca86a37f189b84b79797c313b0c03 (diff) | |
| download | linux-baac167b706600ebe7158acaeb7c489ae9d0bb8b.tar.bz2 | |
pktgen: avoid expensive set_current_state() call in loop
Avoid calling set_current_state() inside the busy-loop in
pktgen_thread_worker(). In case of pkt_dev->delay, then it is still
used/enabled in pktgen_xmit() via the spin() call.
The set_current_state(TASK_INTERRUPTIBLE) uses a xchg, which implicit
is LOCK prefixed. I've measured the asm LOCK operation to take approx
8ns on this E5-2630 CPU. Performance increase corrolate with this
measurement.
Performance data with CLONE_SKB==100000, rx-usecs=30:
(single CPU performance, ixgbe 10Gbit/s, E5-2630)
* Prev: 5454050 pps --> 183.35ns (1/5454050*10^9)
* Now: 5684009 pps --> 175.93ns (1/5684009*10^9)
* Diff: +229959 pps --> -7.42ns
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/pktgen.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/net/core/pktgen.c b/net/core/pktgen.c index fc17a9d309ac..b61f553689b6 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -3407,10 +3407,10 @@ static int pktgen_thread_worker(void *arg) pr_debug("starting pktgen/%d: pid=%d\n", cpu, task_pid_nr(current)); - set_current_state(TASK_INTERRUPTIBLE); - set_freezable(); + __set_current_state(TASK_RUNNING); + while (!kthread_should_stop()) { pkt_dev = next_to_run(t); @@ -3424,8 +3424,6 @@ static int pktgen_thread_worker(void *arg) continue; } - __set_current_state(TASK_RUNNING); - if (likely(pkt_dev)) { pktgen_xmit(pkt_dev); @@ -3456,9 +3454,8 @@ static int pktgen_thread_worker(void *arg) } try_to_freeze(); - - set_current_state(TASK_INTERRUPTIBLE); } + set_current_state(TASK_INTERRUPTIBLE); pr_debug("%s stopping all device\n", t->tsk->comm); pktgen_stop(t); |