[dpdk-dev] [RFC PATCH] Adding RTE_KNI_PREEMPT configuration option

[Marc Sune]

This patch introduces CONFIG_RTE_KNI_PREEMPT flag. When set to 'no', KNI
kernel thread(s) do not call schedule_timeout_interruptible(), which improves
overall KNI performance at the expense of CPU cycles (polling).

Default values is 'yes', maintaining the same behaviour as of now.

Note: this RFC patch is based on v1.7.1, since I was using a 1.7 application.
It will eventually be rebased to 1.8 upon acceptance.

Signed-off-by: Marc Sune <marc.sune at bisdn.de>
---
 config/common_linuxapp                 |    1 +
 lib/librte_eal/linuxapp/kni/kni_misc.c |    4 ++++
 2 files changed, 5 insertions(+)

diff --git a/config/common_linuxapp b/config/common_linuxapp
index 9047975..9cebcf1 100644
--- a/config/common_linuxapp
+++ b/config/common_linuxapp
@@ -382,6 +382,7 @@ CONFIG_RTE_LIBRTE_PIPELINE=y
 # Compile librte_kni
 #
 CONFIG_RTE_LIBRTE_KNI=y
+CONFIG_RTE_KNI_PREEMPT=y
 CONFIG_RTE_KNI_KO_DEBUG=n
 CONFIG_RTE_KNI_VHOST=n
 CONFIG_RTE_KNI_VHOST_MAX_CACHE_SIZE=1024
diff --git a/lib/librte_eal/linuxapp/kni/kni_misc.c 
b/lib/librte_eal/linuxapp/kni/kni_misc.c
index ba77776..e7e6c27 100644
--- a/lib/librte_eal/linuxapp/kni/kni_misc.c
+++ b/lib/librte_eal/linuxapp/kni/kni_misc.c
@@ -229,9 +229,11 @@ kni_thread_single(void *unused)
                        }
                }
                up_read(&kni_list_lock);
+#ifdef RTE_KNI_PREEMPT
                /* reschedule out for a while */
                schedule_timeout_interruptible(usecs_to_jiffies( \
                                KNI_KTHREAD_RESCHEDULE_INTERVAL));
+#endif
        }

        return 0;
@@ -252,8 +254,10 @@ kni_thread_multiple(void *param)
 #endif
                        kni_net_poll_resp(dev);
                }
+#ifdef RTE_KNI_PREEMPT
                schedule_timeout_interruptible(usecs_to_jiffies( \
                                KNI_KTHREAD_RESCHEDULE_INTERVAL));
+#endif
        }

        return 0;
-- 
1.7.10.4