On Fri, May 29, 2020 at 01:01:51PM -0700, Andrii Nakryiko wrote:
> > question though; why are you using xchg() for the commit? Isn't that
> > more expensive than it should be?
> >
> > That is, why isn't that:
> >
> > smp_store_release(&hdr->len, new_len);
> >
> > ? Or are you needing the smp_mb(
On Fri, May 29, 2020 at 10:23 AM Joel Fernandes wrote:
>
> On Thu, May 28, 2020 at 09:38:35PM -0700, Andrii Nakryiko wrote:
> > On Thu, May 28, 2020 at 2:48 PM Joel Fernandes
> > wrote:
> > >
> > > On Mon, May 25, 2020 at 11:38:23AM -0700, Andrii Nakryiko wrote:
> > > > On Mon, May 25, 2020 at 7
On Fri, May 29, 2020 at 5:36 AM Peter Zijlstra wrote:
>
> On Thu, May 28, 2020 at 10:14:21PM -0700, Andrii Nakryiko wrote:
>
> > There is another cluster of applications which are unnecessarily more
> > complicated just for the fact that there is no ordering between
> > correlated events that happ
On Thu, May 28, 2020 at 09:38:35PM -0700, Andrii Nakryiko wrote:
> On Thu, May 28, 2020 at 2:48 PM Joel Fernandes wrote:
> >
> > On Mon, May 25, 2020 at 11:38:23AM -0700, Andrii Nakryiko wrote:
> > > On Mon, May 25, 2020 at 7:53 AM Boqun Feng wrote:
> > > >
> > > > Hi Andrii,
> > > >
> > > > On F
On Thu, May 28, 2020 at 10:14:21PM -0700, Andrii Nakryiko wrote:
> There is another cluster of applications which are unnecessarily more
> complicated just for the fact that there is no ordering between
> correlated events that happen on different CPUs. Per-CPU buffers are
> not well suited for su
On Thu, May 28, 2020 at 3:17 PM Peter Zijlstra wrote:
>
> On Thu, May 28, 2020 at 06:00:47PM -0400, Joel Fernandes wrote:
>
> > Any idea why this choice of locking-based ring buffer implementation in BPF?
> > The ftrace ring buffer can support NMI interruptions as well for writes.
> >
> > Also, is
On Thu, May 28, 2020 at 2:48 PM Joel Fernandes wrote:
>
> On Mon, May 25, 2020 at 11:38:23AM -0700, Andrii Nakryiko wrote:
> > On Mon, May 25, 2020 at 7:53 AM Boqun Feng wrote:
> > >
> > > Hi Andrii,
> > >
> > > On Fri, May 22, 2020 at 12:38:21PM -0700, Andrii Nakryiko wrote:
> > > > On 5/22/20 1
On Thu, May 28, 2020 at 06:00:47PM -0400, Joel Fernandes wrote:
> Any idea why this choice of locking-based ring buffer implementation in BPF?
> The ftrace ring buffer can support NMI interruptions as well for writes.
>
> Also, is it possible for BPF to reuse the ftrace ring buffer implementation
On Mon, May 25, 2020 at 10:21:54AM -0700, Paul E. McKenney wrote:
> On Mon, May 25, 2020 at 07:02:57PM +0200, Peter Zijlstra wrote:
> > On Mon, May 25, 2020 at 08:47:30AM -0700, Paul E. McKenney wrote:
> > > On Mon, May 25, 2020 at 01:25:21PM +0200, Peter Zijlstra wrote:
> >
> > > > That is; how c
On Mon, May 25, 2020 at 11:38:23AM -0700, Andrii Nakryiko wrote:
> On Mon, May 25, 2020 at 7:53 AM Boqun Feng wrote:
> >
> > Hi Andrii,
> >
> > On Fri, May 22, 2020 at 12:38:21PM -0700, Andrii Nakryiko wrote:
> > > On 5/22/20 10:43 AM, Paul E. McKenney wrote:
> > > > On Fri, May 22, 2020 at 10:32:
On Tue, May 26, 2020 at 4:00 PM Akira Yokosawa wrote:
>
> On Tue, 26 May 2020 13:19:36 -0700, Andrii Nakryiko wrote:
> > On Tue, May 26, 2020 at 7:02 AM Akira Yokosawa wrote:
> >>
> >> On Tue, 26 May 2020 19:50:47 +0900, Akira Yokosawa wrote:
> >>> On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakry
On Tue, 26 May 2020 13:19:36 -0700, Andrii Nakryiko wrote:
> On Tue, May 26, 2020 at 7:02 AM Akira Yokosawa wrote:
>>
>> On Tue, 26 May 2020 19:50:47 +0900, Akira Yokosawa wrote:
>>> On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote:
On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wro
On Tue, 26 May 2020 13:15:49 -0700, Andrii Nakryiko wrote:
> On Tue, May 26, 2020 at 3:50 AM Akira Yokosawa wrote:
>>
>> On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote:
>>> On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote:
>> [...]
Yes, that should work.
>>>
>>> Ok, assig
On Tue, May 26, 2020 at 7:02 AM Akira Yokosawa wrote:
>
> On Tue, 26 May 2020 19:50:47 +0900, Akira Yokosawa wrote:
> > On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote:
> >> On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote:
> >>>
> > [...]
> >>> Yes, that should work.
> >>
> >> Ok,
On Tue, May 26, 2020 at 3:50 AM Akira Yokosawa wrote:
>
> On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote:
> > On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote:
> >>
> [...]
> >> Yes, that should work.
> >
> > Ok, assigning to zero didn't work (it still complained about
> > uninitia
On Tue, 26 May 2020 19:50:47 +0900, Akira Yokosawa wrote:
> On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote:
>> On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote:
>>>
> [...]
>>> Yes, that should work.
>>
>> Ok, assigning to zero didn't work (it still complained about
>> uninitialized
On Mon, 25 May 2020 16:31:05 -0700, Andrii Nakryiko wrote:
> On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote:
>>
[...]
>> Yes, that should work.
>
> Ok, assigning to zero didn't work (it still complained about
> uninitialized read), but using a separate int *lenFail to assign to
> rLenPtr wo
On Mon, May 25, 2020 at 3:01 PM Akira Yokosawa wrote:
>
> On Mon, 25 May 2020 11:31:27 -0700, Andrii Nakryiko wrote:
> > On Sun, May 24, 2020 at 5:09 AM Akira Yokosawa wrote:
> >>
> >> On Fri, 22 May 2020 12:38:21 -0700, Andrii Nakryiko wrote:
> >>> On 5/22/20 10:43 AM, Paul E. McKenney wrote:
>
On Mon, 25 May 2020 11:31:27 -0700, Andrii Nakryiko wrote:
> On Sun, May 24, 2020 at 5:09 AM Akira Yokosawa wrote:
>>
>> On Fri, 22 May 2020 12:38:21 -0700, Andrii Nakryiko wrote:
>>> On 5/22/20 10:43 AM, Paul E. McKenney wrote:
On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
On Mon, May 25, 2020 at 7:53 AM Boqun Feng wrote:
>
> Hi Andrii,
>
> On Fri, May 22, 2020 at 12:38:21PM -0700, Andrii Nakryiko wrote:
> > On 5/22/20 10:43 AM, Paul E. McKenney wrote:
> > > On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
> > > > On Fri, May 22, 2020 at 11:44:07AM +0200,
On Sun, May 24, 2020 at 5:09 AM Akira Yokosawa wrote:
>
> On Fri, 22 May 2020 12:38:21 -0700, Andrii Nakryiko wrote:
> > On 5/22/20 10:43 AM, Paul E. McKenney wrote:
> >> On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
> >>> On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrot
On Mon, May 25, 2020 at 10:21:54AM -0700, Paul E. McKenney wrote:
> On Mon, May 25, 2020 at 07:02:57PM +0200, Peter Zijlstra wrote:
> > On Mon, May 25, 2020 at 08:47:30AM -0700, Paul E. McKenney wrote:
> > > On Mon, May 25, 2020 at 01:25:21PM +0200, Peter Zijlstra wrote:
> >
> > > > That is; how c
On Mon, May 25, 2020 at 07:02:57PM +0200, Peter Zijlstra wrote:
> On Mon, May 25, 2020 at 08:47:30AM -0700, Paul E. McKenney wrote:
> > On Mon, May 25, 2020 at 01:25:21PM +0200, Peter Zijlstra wrote:
>
> > > That is; how can you use a spinlock on the producer side at all?
> >
> > So even trylock
On Mon, May 25, 2020 at 08:47:30AM -0700, Paul E. McKenney wrote:
> On Mon, May 25, 2020 at 01:25:21PM +0200, Peter Zijlstra wrote:
> > That is; how can you use a spinlock on the producer side at all?
>
> So even trylock is now forbidden in NMI handlers? If so, why?
The litmus tests don't have
On Mon, May 25, 2020 at 01:25:21PM +0200, Peter Zijlstra wrote:
> On Fri, May 22, 2020 at 12:38:21PM -0700, Andrii Nakryiko wrote:
> > On 5/22/20 10:43 AM, Paul E. McKenney wrote:
> > > On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
>
> > > > Also, what use is a spinlock that is acces
Hi Andrii,
On Fri, May 22, 2020 at 12:38:21PM -0700, Andrii Nakryiko wrote:
> On 5/22/20 10:43 AM, Paul E. McKenney wrote:
> > On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
> > > On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
> > > > On Thu, May 21, 2020 at 05:38:50P
On Fri, May 22, 2020 at 12:38:21PM -0700, Andrii Nakryiko wrote:
> On 5/22/20 10:43 AM, Paul E. McKenney wrote:
> > On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
> > > Also, what use is a spinlock that is accessed in only one thread?
> >
> > Multiple writers synchronize via the spin
On Fri, 22 May 2020 12:38:21 -0700, Andrii Nakryiko wrote:
> On 5/22/20 10:43 AM, Paul E. McKenney wrote:
>> On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
>>> On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenne
On 5/22/20 10:43 AM, Paul E. McKenney wrote:
On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
Hello!
Just wanted to call your attention to some pretty c
On Fri, May 22, 2020 at 10:36:09AM -0400, Alan Stern wrote:
> On Fri, May 22, 2020 at 03:56:59AM -0700, Paul E. McKenney wrote:
> > On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
> > > On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
> > > > Hello!
> > > >
> > > >
On Fri, May 22, 2020 at 10:32:01AM -0400, Alan Stern wrote:
> On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
> > On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
> > > Hello!
> > >
> > > Just wanted to call your attention to some pretty cool and pretty serious
> >
On Fri, May 22, 2020 at 03:56:59AM -0700, Paul E. McKenney wrote:
> On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
> > On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
> > > Hello!
> > >
> > > Just wanted to call your attention to some pretty cool and pretty serio
On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
> On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
> > Hello!
> >
> > Just wanted to call your attention to some pretty cool and pretty serious
> > litmus tests that Andrii did as part of his BPF ring-buffer work:
> >
On Fri, May 22, 2020 at 11:44:07AM +0200, Peter Zijlstra wrote:
> On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
> > Hello!
> >
> > Just wanted to call your attention to some pretty cool and pretty serious
> > litmus tests that Andrii did as part of his BPF ring-buffer work:
> >
On Thu, May 21, 2020 at 05:38:50PM -0700, Paul E. McKenney wrote:
> Hello!
>
> Just wanted to call your attention to some pretty cool and pretty serious
> litmus tests that Andrii did as part of his BPF ring-buffer work:
>
> https://lore.kernel.org/bpf/20200517195727.279322-3-andr...@fb.com/
>
>
Hello!
Just wanted to call your attention to some pretty cool and pretty serious
litmus tests that Andrii did as part of his BPF ring-buffer work:
https://lore.kernel.org/bpf/20200517195727.279322-3-andr...@fb.com/
Thoughts?
Thanx, Paul
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