Re: [dpdk-dev] [PATCH] Adding RTE_KNI_PREEMPT configuration option

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Feb 10, 2015 at 12:59:29PM +0100, Marc Sune wrote:
> This patch of Nov 2014 hasn't been yet ACKed/NACKed. Could someone please
> give some quick feedback?
> 
> Thanks
> marc
> 
> On 07/11/14 12:00, Marc Sune wrote:
> >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.
> >
> >Signed-off-by: Marc Sune <marc.sune@bisdn.de>

Although a better option would be to have a runtime setting, this is still
an improvement over what we have.

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

> >---
> >  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 57b61c9..24b529d 100644
> >--- a/config/common_linuxapp
> >+++ b/config/common_linuxapp
> >@@ -380,6 +380,7 @@ 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;
>