On Mon, May 16, 2016 at 6:10 AM, Paolo Abeni wrote:
>
> I'm sorry for the not-so-prompt reply. I had to use a different H/W, so
> I had to re-run the tests with all the patch flavors to get comparable
> results.
>
> While I can confirm that adding the '!ksoftirqd_running()' condition
> improves th
On Fri, 2016-05-13 at 10:36 -0700, Eric Dumazet wrote:
> On Fri, May 13, 2016 at 10:19 AM, Paolo Abeni wrote:
>
> > The difference is small, in the noise range:
> >
> > [with this patch applied]
> > super_netperf 100 -H 192.168.122.1 -t UDP_STREAM -l 60 -- -m 1
> > 9.00
> >
> > [adding the test i
On Fri, May 13, 2016 at 10:19 AM, Paolo Abeni wrote:
> The difference is small, in the noise range:
>
> [with this patch applied]
> super_netperf 100 -H 192.168.122.1 -t UDP_STREAM -l 60 -- -m 1
> 9.00
>
> [adding the test into __local_bh_enable_ip(), too]
> super_netperf 100 -H 192.168.122.1 -t
On Fri, 2016-05-13 at 10:03 -0700, Eric Dumazet wrote:
> On Fri, May 13, 2016 at 9:50 AM, Paolo Abeni wrote:
>
> >> Indeed, and the patch looks quite simple now ;)
> >>
> >> diff --git a/kernel/softirq.c b/kernel/softirq.c
> >> index
> >> 17caf4b63342d7839528f367b283a386413b0362..23c364485d03618
On Fri, May 13, 2016 at 9:50 AM, Paolo Abeni wrote:
>> Indeed, and the patch looks quite simple now ;)
>>
>> diff --git a/kernel/softirq.c b/kernel/softirq.c
>> index
>> 17caf4b63342d7839528f367b283a386413b0362..23c364485d03618773c385d943c0ef39f5931d09
>> 100644
>> --- a/kernel/softirq.c
>> +++
On Wed, 2016-05-11 at 14:56 -0700, Eric Dumazet wrote:
> On Wed, 2016-05-11 at 08:55 +0200, Peter Zijlstra wrote:
> > On Tue, May 10, 2016 at 03:51:37PM -0700, Eric Dumazet wrote:
> > > diff --git a/kernel/softirq.c b/kernel/softirq.c
> > > index 17caf4b63342..22463217e3cf 100644
> > > --- a/kernel
On Thu, 2016-05-12 at 22:58 +0200, Paolo Abeni wrote:
> On Thu, 2016-05-12 at 13:49 -0700, Eric Dumazet wrote:
> > On Thu, 2016-05-12 at 22:07 +0200, Paolo Abeni wrote:
> >
> > > > > static inline bool ksoftirqd_running(void)
> > > > > {
> > > > > return __this_cpu_read(ksoftirqd)->state ==
On Thu, 2016-05-12 at 13:49 -0700, Eric Dumazet wrote:
> On Thu, 2016-05-12 at 22:07 +0200, Paolo Abeni wrote:
>
> > > > static inline bool ksoftirqd_running(void)
> > > > {
> > > > return __this_cpu_read(ksoftirqd)->state == TASK_RUNNING;
> >
> > here something like:
> >
> > struct
On Thu, 2016-05-12 at 22:07 +0200, Paolo Abeni wrote:
> > > static inline bool ksoftirqd_running(void)
> > > {
> > > return __this_cpu_read(ksoftirqd)->state == TASK_RUNNING;
>
> here something like:
>
> struct task_struct *tsk = __this_cpu_read(ksoftirqd);
> return tsk && (tsk->
On Wed, 2016-05-11 at 14:56 -0700, Eric Dumazet wrote:
> On Wed, 2016-05-11 at 08:55 +0200, Peter Zijlstra wrote:
> > On Tue, May 10, 2016 at 03:51:37PM -0700, Eric Dumazet wrote:
> > > diff --git a/kernel/softirq.c b/kernel/softirq.c
> > > index 17caf4b63342..22463217e3cf 100644
> > > --- a/kernel
On 11.05.2016 16:45, Eric Dumazet wrote:
> On Wed, May 11, 2016 at 7:38 AM, Paolo Abeni wrote:
>
>> Uh, we have likely the same issue in the net_rx_action() function, which
>> also execute with bh disabled and check for jiffies changes even on
>> single core hosts ?!?
>
> That is why we have a l
On Wed, 2016-05-11 at 08:55 +0200, Peter Zijlstra wrote:
> On Tue, May 10, 2016 at 03:51:37PM -0700, Eric Dumazet wrote:
> > diff --git a/kernel/softirq.c b/kernel/softirq.c
> > index 17caf4b63342..22463217e3cf 100644
> > --- a/kernel/softirq.c
> > +++ b/kernel/softirq.c
> > @@ -56,6 +56,7 @@ EXPOR
On Tue, 2016-05-10 at 14:53 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 17:35 -0400, Rik van Riel wrote:
>
> > You might need another one of these in invoke_softirq()
> >
>
> Excellent.
>
> I gave it a quick try (without your suggestion), and host seems to
> survive a stress test.
Well,
On Wed, 2016-05-11 at 07:40 -0700, Eric Dumazet wrote:
> On Wed, May 11, 2016 at 6:13 AM, Hannes Frederic Sowa
> wrote:
>
> > This looks racy to me as the ksoftirqd could be in the progress to stop
> > and we would miss another softirq invocation.
>
> Looking at smpboot_thread_fn(), it looks fin
On Wed, 2016-05-11 at 07:40 -0700, Eric Dumazet wrote:
> On Wed, May 11, 2016 at 6:13 AM, Hannes Frederic Sowa
> wrote:
>
> > This looks racy to me as the ksoftirqd could be in the progress to
> > stop
> > and we would miss another softirq invocation.
>
> Looking at smpboot_thread_fn(), it looks
On Wed, May 11, 2016 at 7:38 AM, Paolo Abeni wrote:
> Uh, we have likely the same issue in the net_rx_action() function, which
> also execute with bh disabled and check for jiffies changes even on
> single core hosts ?!?
That is why we have a loop break after netdev_budget=300 packets.
And a sys
On Wed, May 11, 2016 at 6:13 AM, Hannes Frederic Sowa
wrote:
> This looks racy to me as the ksoftirqd could be in the progress to stop
> and we would miss another softirq invocation.
Looking at smpboot_thread_fn(), it looks fine :
if (!ht->thread_should_run(td->cpu)) {
On Wed, 2016-05-11 at 06:08 -0700, Eric Dumazet wrote:
> On Wed, 2016-05-11 at 11:48 +0200, Paolo Abeni wrote:
> > Hi Eric,
> > On Tue, 2016-05-10 at 15:51 -0700, Eric Dumazet wrote:
> > > On Wed, 2016-05-11 at 00:32 +0200, Hannes Frederic Sowa wrote:
> > >
> > > > Not only did we want to present
On 11.05.2016 15:39, Hannes Frederic Sowa wrote:
> I am fine with that. It is us to show clear benefits or use cases for
> that. If we fail with that, no problem at all that the patches get
> rejected, we don't want to add bloat to the kernel, for sure! At this
> point I still think a possibility t
Hi all,
On 11.05.2016 15:08, Eric Dumazet wrote:
> On Wed, 2016-05-11 at 11:48 +0200, Paolo Abeni wrote:
>> Hi Eric,
>> On Tue, 2016-05-10 at 15:51 -0700, Eric Dumazet wrote:
>>> On Wed, 2016-05-11 at 00:32 +0200, Hannes Frederic Sowa wrote:
>>>
Not only did we want to present this solely as
On 11.05.2016 08:55, Peter Zijlstra wrote:
> On Tue, May 10, 2016 at 03:51:37PM -0700, Eric Dumazet wrote:
>> diff --git a/kernel/softirq.c b/kernel/softirq.c
>> index 17caf4b63342..22463217e3cf 100644
>> --- a/kernel/softirq.c
>> +++ b/kernel/softirq.c
>> @@ -56,6 +56,7 @@ EXPORT_SYMBOL(irq_stat);
On Wed, 2016-05-11 at 11:48 +0200, Paolo Abeni wrote:
> Hi Eric,
> On Tue, 2016-05-10 at 15:51 -0700, Eric Dumazet wrote:
> > On Wed, 2016-05-11 at 00:32 +0200, Hannes Frederic Sowa wrote:
> >
> > > Not only did we want to present this solely as a bugfix but also as as
> > > performance enhancemen
Hi Eric,
On Tue, 2016-05-10 at 15:51 -0700, Eric Dumazet wrote:
> On Wed, 2016-05-11 at 00:32 +0200, Hannes Frederic Sowa wrote:
>
> > Not only did we want to present this solely as a bugfix but also as as
> > performance enhancements in case of virtio (as you can see in the cover
> > letter). Giv
On Tue, May 10, 2016 at 03:51:37PM -0700, Eric Dumazet wrote:
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index 17caf4b63342..22463217e3cf 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -56,6 +56,7 @@ EXPORT_SYMBOL(irq_stat);
> static struct softirq_action softirq_vec[NR_SO
On Wed, 2016-05-11 at 00:32 +0200, Hannes Frederic Sowa wrote:
> Not only did we want to present this solely as a bugfix but also as as
> performance enhancements in case of virtio (as you can see in the cover
> letter). Given that a long time ago there was a tendency to remove
> softirqs complete
On Tue, 2016-05-10 at 15:02 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 14:53 -0700, Eric Dumazet wrote:
> > On Tue, 2016-05-10 at 17:35 -0400, Rik van Riel wrote:
> >
> > > You might need another one of these in invoke_softirq()
> > >
> >
> > Excellent.
> >
> > I gave it a quick try (wi
On 10.05.2016 23:09, Eric Dumazet wrote:
> On Tue, May 10, 2016 at 1:46 PM, Hannes Frederic Sowa
> wrote:
>
>> I agree here, but I don't think this patch particularly is a lot of
>> bloat and something very interesting people can play with and extend upon.
>>
>
> Sure, very rarely patch authors
On Tue, 2016-05-10 at 14:53 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 17:35 -0400, Rik van Riel wrote:
>
> > You might need another one of these in invoke_softirq()
> >
>
> Excellent.
>
> I gave it a quick try (without your suggestion), and host seems to
> survive a stress test.
>
> O
On Tue, 2016-05-10 at 14:53 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 17:35 -0400, Rik van Riel wrote:
>
> >
> > You might need another one of these in invoke_softirq()
> >
> Excellent.
>
> I gave it a quick try (without your suggestion), and host seems to
> survive a stress test.
>
>
On Tue, 2016-05-10 at 17:35 -0400, Rik van Riel wrote:
> You might need another one of these in invoke_softirq()
>
Excellent.
I gave it a quick try (without your suggestion), and host seems to
survive a stress test.
Of course we do have to fix these problems :
[ 147.781629] NOHZ: local_softi
On Tue, 2016-05-10 at 14:31 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 14:09 -0700, Eric Dumazet wrote:
> >
> > On Tue, May 10, 2016 at 1:46 PM, Hannes Frederic Sowa
> > wrote:
> >
> > >
> > > I agree here, but I don't think this patch particularly is a lot
> > > of
> > > bloat and some
On Tue, 2016-05-10 at 14:09 -0700, Eric Dumazet wrote:
> On Tue, May 10, 2016 at 1:46 PM, Hannes Frederic Sowa
> wrote:
>
> > I agree here, but I don't think this patch particularly is a lot of
> > bloat and something very interesting people can play with and extend upon.
> >
>
> Sure, very rare
On Tue, May 10, 2016 at 1:46 PM, Hannes Frederic Sowa
wrote:
> I agree here, but I don't think this patch particularly is a lot of
> bloat and something very interesting people can play with and extend upon.
>
Sure, very rarely patch authors think their stuff is bloat.
I prefer to fix kernel so
On Tue, 2016-05-10 at 16:52 -0400, David Miller wrote:
> From: Rik van Riel
> Date: Tue, 10 May 2016 16:50:56 -0400
>
> > On Tue, 2016-05-10 at 16:45 -0400, David Miller wrote:
> >> From: Paolo Abeni
> >> Date: Tue, 10 May 2016 22:22:50 +0200
> >>
> >> > On Tue, 2016-05-10 at 09:08 -0700, Eric
From: Rik van Riel
Date: Tue, 10 May 2016 16:50:56 -0400
> On Tue, 2016-05-10 at 16:45 -0400, David Miller wrote:
>> From: Paolo Abeni
>> Date: Tue, 10 May 2016 22:22:50 +0200
>>
>> > On Tue, 2016-05-10 at 09:08 -0700, Eric Dumazet wrote:
>> >> On Tue, 2016-05-10 at 18:03 +0200, Paolo Abeni wro
On Tue, 2016-05-10 at 16:45 -0400, David Miller wrote:
> From: Paolo Abeni
> Date: Tue, 10 May 2016 22:22:50 +0200
>
> > On Tue, 2016-05-10 at 09:08 -0700, Eric Dumazet wrote:
> >> On Tue, 2016-05-10 at 18:03 +0200, Paolo Abeni wrote:
> >>
> >> > If a single core host is under network flood, i.e
Hello,
On 10.05.2016 16:29, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 16:11 +0200, Paolo Abeni wrote:
>> Currently, the softirq loop can be scheduled both inside the ksofirqd kernel
>> thread and inside any running process. This makes nearly impossible for the
>> process scheduler to balance in
From: Paolo Abeni
Date: Tue, 10 May 2016 22:22:50 +0200
> On Tue, 2016-05-10 at 09:08 -0700, Eric Dumazet wrote:
>> On Tue, 2016-05-10 at 18:03 +0200, Paolo Abeni wrote:
>>
>> > If a single core host is under network flood, i.e. ksoftirqd is
>> > scheduled and it eventually (after processing ~64
On Tue, 2016-05-10 at 17:57 +0200, Thomas Gleixner wrote:
> On Tue, 10 May 2016, Paolo Abeni wrote:
>
> Nice patch set and very promising results!
>
> > At this point we are not really sure if we should go with this simpler
> > approach by putting NAPI itself into kthreads or leverage the thread
On Tue, 2016-05-10 at 09:08 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 18:03 +0200, Paolo Abeni wrote:
>
> > If a single core host is under network flood, i.e. ksoftirqd is
> > scheduled and it eventually (after processing ~640 packets) will let the
> > user space process run. The latter w
On Tue, 2016-05-10 at 18:03 +0200, Paolo Abeni wrote:
> If a single core host is under network flood, i.e. ksoftirqd is
> scheduled and it eventually (after processing ~640 packets) will let the
> user space process run. The latter will execute a syscall to receive a
> packet, which will have to d
Hi,
On Tue, 2016-05-10 at 07:29 -0700, Eric Dumazet wrote:
> On Tue, 2016-05-10 at 16:11 +0200, Paolo Abeni wrote:
> > Currently, the softirq loop can be scheduled both inside the ksofirqd kernel
> > thread and inside any running process. This makes nearly impossible for the
> > process scheduler
On Tue, 10 May 2016, Paolo Abeni wrote:
Nice patch set and very promising results!
> At this point we are not really sure if we should go with this simpler
> approach by putting NAPI itself into kthreads or leverage the threadirqs
> function by putting the whole interrupt into a thread and signa
From: Eric Dumazet
Date: Tue, 10 May 2016 07:29:50 -0700
> We already have ksoftirqd to normally cope with the case you are
> describing.
>
> If it is not working as intended, please identify the bugs and fix them,
> instead of adding yet another tests in fast path and extra complexity in
> the
Currently, the softirq loop can be scheduled both inside the ksofirqd kernel
thread and inside any running process. This makes nearly impossible for the
process scheduler to balance in a fair way the amount of time that
a given core spends performing the softirq loop.
Under high network load, the
On Tue, 2016-05-10 at 16:11 +0200, Paolo Abeni wrote:
> Currently, the softirq loop can be scheduled both inside the ksofirqd kernel
> thread and inside any running process. This makes nearly impossible for the
> process scheduler to balance in a fair way the amount of time that
> a given core spen
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