From: Bruce Richardson <bruce.richardson@intel.com>
To: Marc Sune <marc.sune@bisdn.de>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] Adding RTE_KNI_PREEMPT configuration option
Date: Wed, 11 Feb 2015 14:27:39 +0000 [thread overview]
Message-ID: <20150211142739.GA7720@bricha3-MOBL3> (raw)
In-Reply-To: <54DB4A81.5040106@bisdn.de>
On Wed, Feb 11, 2015 at 01:26:41PM +0100, Marc Sune wrote:
>
> On 11/02/15 02:54, Zhang, Helin wrote:
> >
> >>-----Original Message-----
> >>From: Richardson, Bruce
> >>Sent: Tuesday, February 10, 2015 9:24 PM
> >>To: Marc Sune
> >>Cc: dev@dpdk.org; Zhang, Helin
> >>Subject: Re: [dpdk-dev] [PATCH] Adding RTE_KNI_PREEMPT configuration
> >>option
> >>
> >>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;
> >As Bruce indicated, it would be better to do that at runtime, we can
> >add a config in struct rte_kni_conf, which will be copied to
> >struct rte_kni_device_info, then kernel space will know the configuration.
> >This way, we can enable/disable PREEMPT during KNI instance allocation time.
>
> As I said before, I see the point on having it at runtime and I agree.
>
> However, rte_kni_device_info is a struct that is per interface, not for the
> entire KNI subsystem, so it is kind of abusing to add a flag there when only
> will be used once, at bootstrap. To do it "properly" we should create a new
> ioctl() call IMHO.
>
> >Anyway, it can be done now or later.
>
> So, do we integrate the current patch, as acked by Bruce before?
>
> Marc
I'd like to see it go in, as a step forward, rather than not having it at all
because it's not quite perfect.
One suggestion might be to have the compile time setting be
"CONFIG_RTE_KNI_PREEMPT_DEFAULT" rather than just "CONFIG_RTE_KNI_PREEMPT". This
would mean that we would not need to remove the setting later if we do add a
runtime option, as the setting only specified the default value rather than
the final value. :-)
/Bruce
next prev parent reply other threads:[~2015-02-11 14:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-07 11:00 Marc Sune
2015-02-10 11:59 ` Marc Sune
2015-02-10 12:02 ` Bruce Richardson
2015-02-10 12:21 ` Marc Sune
2015-02-10 13:22 ` Bruce Richardson
2015-02-10 18:06 ` Marc Sune
2015-02-10 13:24 ` Bruce Richardson
2015-02-11 1:54 ` Zhang, Helin
2015-02-11 12:26 ` Marc Sune
2015-02-11 14:27 ` Bruce Richardson [this message]
2015-02-12 9:25 ` Marc Sune
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