On Tue, Sep 21, 2010 at 04:47:45PM -0400, Kyle Moffett wrote:
> Well how about something much more straightforward:
I am about to post another patch set for discussion, so please comment
on it when it appears.
Thanks,
Richard
___
Linuxppc-dev mailing li
On Fri, Aug 27, 2010 at 18:30, John Stultz wrote:
> On one side, there is the view that the kernel should abstract and hide
> the hardware details to increase app portability. And the other is that
> the raw hardware details should be exposed, so the OS stays out of the
> way.
>
> Neither of these
Hi Richard,
1. Character device
2. POSIX clock with dynamic ids
Please, just take your pick ;^)
Just to reopen this nearly dead but very interesting thread: I'm happy
with every solution that has no impact on the accuracy of the PTP clock.
If I can choose, I would prefer the POSIX clock wi
On Fri, Aug 27, 2010 at 03:30:39PM -0700, John Stultz wrote:
> On Fri, 2010-08-27 at 14:38 +0200, Richard Cochran wrote:
> > We have not introduced new PPS interface. We use existing PPS subsystem.
>
> Doesn't the pps subsystem have its own way to control the pps signal
> interrupt? I'm not totall
Alan Cox wrote:
The master node in a PTP network probably takes its time from a
precise external time source, like GPS. The GPS provides a 1 PPS
directly to the PTP clock hardware, which latches the PTP hardware
clock time on the PPS edge. This provides one sample as input to a
clock servo (in th
On Fri, 2010-08-27 at 14:38 +0200, Richard Cochran wrote:
> On Mon, Aug 23, 2010 at 01:08:45PM -0700, john stultz wrote:
> > On Thu, 2010-08-19 at 07:55 +0200, Richard Cochran wrote:
> > > The clockid_t CLOCK_PTP will be arch-neutral.
> >
> > Sure, but are they conceptually neutral? There are othe
On Fri, 2010-08-27 at 14:03 +0200, Arnd Bergmann wrote:
> On Friday 27 August 2010, Richard Cochran wrote:
> > On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote:
> > > On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote:
> > > > On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann
On Fri, 2010-08-27 at 13:08 +0200, Richard Cochran wrote:
> On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote:
> > On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote:
> > > On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote:
> > > > My point was that a syscall is better t
On Fri, Aug 27, 2010 at 8:06 AM, Alan Cox wrote
> > > system time bimble track a source makes sense just as with NTP but
> making
> > > it a new clock seems the wrong model extending a non-too-bright API
> when
> > > you can just put the time sources in a file tree.
> >
> > Don't get your meaning
Hi!
I'd like to add my two cents about the discussion. Just to shortly
introduce myself: I'm working with PTP since version 2002 (now 2008 or
PTPv2) and I'm developing matching network cards, drivers, and also
sometimes a bit of the stack.
I always had the problem of different HW implementations
In message: <20100827140205.ga3...@riccoc20.at.omicron.at>
Richard Cochran writes:
: On Fri, Aug 27, 2010 at 01:41:54PM +0100, Alan Cox wrote:
: > > The master node in a PTP network probably takes its time from a
: > > precise external time source, like GPS. The GPS provides a 1 PPS
:
> Sorry for causing confusion, but please understand "a hardware clock
> with timestamping capabilities than can be used for PTP support"
> whenever I wrote "PTP" or "PTP clock."
Ok that makes sense.
>
> Well, what I just said is not entirely true.
> most are bound to the PTP protocol. That may c
On Fri, Aug 27, 2010 at 02:38:44PM +0100, Alan Cox wrote:
> > 2007. If we can justify adding a clock id in this case, surely we can
> > add one for PTP as well!
>
> But PTP isn't really a clock - its a time sync protocol. You can (and may
> need to) have multiple clocks of this form on the same ho
> To tell the truth, my original motivation for the patch set was to
> support PTP clocks and applications. I don't think that is such a bad
ptp *clocks*
> idea. After all, the adjtimex interface was added just to support NTP.
>
> At the same time, I can understand the desire to have a generic
>
On Fri, Aug 27, 2010 at 01:41:54PM +0100, Alan Cox wrote:
> > The master node in a PTP network probably takes its time from a
> > precise external time source, like GPS. The GPS provides a 1 PPS
> > directly to the PTP clock hardware, which latches the PTP hardware
> > clock time on the PPS edge. T
> 2007. If we can justify adding a clock id in this case, surely we can
> add one for PTP as well!
But PTP isn't really a clock - its a time sync protocol. You can (and may
need to) have multiple clocks of this form on the same host because it's
master based and you may have to deal with multiple
> The master node in a PTP network probably takes its time from a
> precise external time source, like GPS. The GPS provides a 1 PPS
> directly to the PTP clock hardware, which latches the PTP hardware
> clock time on the PPS edge. This provides one sample as input to a
> clock servo (in the PTPd)
> > So if the clock_adjtime interface is needed, it would seem best for it
> > to be generic enough to support not only PTP, but also the NTP kernel
> > PLL.
>
> For the proposed clock_adjime, what else is needed to support clock
> adjustment in general?
Multiple PLLs, at least with containers an
On Mon, Aug 23, 2010 at 01:08:45PM -0700, john stultz wrote:
> On Thu, 2010-08-19 at 07:55 +0200, Richard Cochran wrote:
> > The clockid_t CLOCK_PTP will be arch-neutral.
>
> Sure, but are they conceptually neutral? There are other clock
> synchronization algorithms out there. Will they need their
On Friday 27 August 2010, Richard Cochran wrote:
> On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote:
> > On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote:
> > > On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote:
> > > > Have you considered passing a struct timex inste
On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote:
> On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote:
> > On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote:
> > > My point was that a syscall is better than an ioctl based interface here,
> > > which I definitely still
On Thu, Aug 26, 2010 at 06:57:49PM -0700, john stultz wrote:
> On Wed, 2010-08-25 at 11:40 +0200, Christian Riesch wrote:
> > 2) Master clock:
> > We have one or more network ports. Our system has a really good clock
> > (ovenized quartz crystal, an atomic clock, a GPS timing receiver...)
> > and i
On Wed, 2010-08-25 at 11:40 +0200, Christian Riesch wrote:
> What you describe here is only one of the use cases. If the hardware
> has a single network port and operates as a PTP slave, it timestamps
> the PTP packets that are sent and received and subsequently uses these
> timestamps and the info
On Mon, Aug 23, 2010 at 10:08 PM, john stultz wrote:
> On Thu, 2010-08-19 at 07:55 +0200, Richard Cochran wrote:
>> On Wed, Aug 18, 2010 at 05:12:56PM -0700, john stultz wrote:
>> > Again, my knowledge in the networking stack is pretty limited. But it
>> > would seem that having an interface that
Hello!
I'm curious if its possible to do the PTP hardware offset/adjustment
calculation in a module internally to the kernel? That would allow the
PPS interface to still be used to sync the system time, and not expose
additional interfaces.
Just my 2 cents on this issue. PTP is very often used i
On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote:
> On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote:
> > My point was that a syscall is better than an ioctl based interface here,
> > which I definitely still think. Given that John knows much more about
> > clocks than I do, we
Sorry for the slow response here, I got busy with other work at the end
of last week.
On Thu, 2010-08-19 at 07:55 +0200, Richard Cochran wrote:
> On Wed, Aug 18, 2010 at 05:12:56PM -0700, john stultz wrote:
> > On Wed, 2010-08-18 at 09:19 +0200, Richard Cochran wrote:
> > > The timer/alarm stuff i
On Thursday 19 August 2010, Ira W. Snyder wrote:
> Perhaps you were thinking of the vhost example (taken from
> drivers/vhost/Kconfig):
>
> config VHOST_NET
> tristate "Host kernel accelerator for virtio net (EXPERIMENTAL)"
> depends on NET && EVENTFD && (TUN || !TUN) && (MACVTAP |
On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote:
> My point was that a syscall is better than an ioctl based interface here,
> which I definitely still think. Given that John knows much more about
> clocks than I do, we still need to get agreement on the question that
> he raised, whi
On Thu, Aug 19, 2010 at 02:29:49PM +0200, Arnd Bergmann wrote:
> On Thursday 19 August 2010, Richard Cochran wrote:
> >
> > On Wed, Aug 18, 2010 at 05:02:03PM +0200, Arnd Bergmann wrote:
> > > You might want to use callbacks for these system calls that you
> > > can register to at module load time
On Thursday 19 August 2010, Richard Cochran wrote:
>
> On Wed, Aug 18, 2010 at 05:02:03PM +0200, Arnd Bergmann wrote:
> > You might want to use callbacks for these system calls that you
> > can register to at module load time, like it is done for the
> > existing syscalls.
>
> Can you point me to
On Thursday 19 August 2010, Richard Cochran wrote:
> On Wed, Aug 18, 2010 at 05:12:56PM -0700, john stultz wrote:
> > On Wed, 2010-08-18 at 09:19 +0200, Richard Cochran wrote:
> > > The timer/alarm stuff is "ancillary" and is not at all necessary. It
> > > is just a "nice to have." I will happily r
On Wed, Aug 18, 2010 at 05:02:03PM +0200, Arnd Bergmann wrote:
> You might want to use callbacks for these system calls that you
> can register to at module load time, like it is done for the
> existing syscalls.
Can you point me to a specific example?
> The simpler way (e.g. for testing) is usin
On Wed, Aug 18, 2010 at 05:12:56PM -0700, john stultz wrote:
> On Wed, 2010-08-18 at 09:19 +0200, Richard Cochran wrote:
> > The timer/alarm stuff is "ancillary" and is not at all necessary. It
> > is just a "nice to have." I will happily remove it, if it is too
> > troubling for people.
>
> If th
On Wed, 2010-08-18 at 09:19 +0200, Richard Cochran wrote:
> On Tue, Aug 17, 2010 at 05:22:43PM -0700, john stultz wrote:
>>
> > So while to me, it think it would be more ideal (or maybe just less
> > different) to have a read-only interface (like the RTC), leaving PTPd to
> > manage offset calculat
On Wednesday 18 August 2010, Richard Cochran wrote:
> On Tue, Aug 17, 2010 at 01:36:29PM +0200, Arnd Bergmann wrote:
> > On Tuesday 17 August 2010, Richard Cochran wrote:
> > > I've been looking at offering the PTP clock as a posix clock, and it
> > > is not as hard as I first thought. The PTP cloc
On Tue, Aug 17, 2010 at 01:36:29PM +0200, Arnd Bergmann wrote:
> On Tuesday 17 August 2010, Richard Cochran wrote:
> > I've been looking at offering the PTP clock as a posix clock, and it
> > is not as hard as I first thought. The PTP clock or clocks just have
> > to be registered as one of the pos
On Tue, Aug 17, 2010 at 05:22:43PM -0700, john stultz wrote:
> Why would system time not be adjusted to the PTP time?
>
> This is my main concern, that we're presenting a fractured API to
> userland. Suddenly there isn't just system time, but ptp time as well,
> and possibly multiple different ptp
On Tue, 2010-08-17 at 13:36 +0200, Arnd Bergmann wrote:
> On Tuesday 17 August 2010, Richard Cochran wrote:
> > On Tue, Aug 17, 2010 at 09:25:55AM +, Arnd Bergmann wrote:
> > > Another difference is that we generally use ioctl for devices that can
> > > be enumerated, while syscalls are for sys
On Tue, 2010-08-17 at 10:53 +0200, Richard Cochran wrote:
> On Mon, Aug 16, 2010 at 12:24:48PM -0700, john stultz wrote:
> > 3) I'm not sure I see the benefit of being able to have multiple
> > frequency corrected time domains. In other words, what benefit would
> > you get from adjusting a PTP cl
On Tuesday 17 August 2010, Richard Cochran wrote:
> On Tue, Aug 17, 2010 at 09:25:55AM +, Arnd Bergmann wrote:
> > Another difference is that we generally use ioctl for devices that can
> > be enumerated, while syscalls are for system services that are not tied to
> > a specific device. This ar
On Tue, Aug 17, 2010 at 09:25:55AM +, Arnd Bergmann wrote:
> Another difference is that we generally use ioctl for devices that can
> be enumerated, while syscalls are for system services that are not tied to
> a specific device. This argument works both ways for PTP IMHO: On the one
> hand you
On Tuesday 17 August 2010, Richard Cochran wrote:
> > Why did you not want to add syscalls? Adding ioctls instead of syscalls
> > does not make the interface better, just less visible.
>
> I bet that, had I posted patch set with new syscalls, someone would
> have said, "You are adding new syscalls
On Mon, Aug 16, 2010 at 12:24:48PM -0700, john stultz wrote:
> 3) I'm not sure I see the benefit of being able to have multiple
> frequency corrected time domains. In other words, what benefit would
> you get from adjusting a PTP clock's frequency instead of just
> adjusting the system's time freq
On Mon, Aug 16, 2010 at 09:59:39PM +0200, Arnd Bergmann wrote:
> Why does it matter how long it takes to read the clock? I wasn't thinking
> of replacing the system clock with this, just exposing the additional
> clock as a new clockid_t value that can be accessed using the existing
> syscalls.
Ok
On Monday 16 August 2010 21:00:03 Richard Cochran wrote:
>
> On Mon, Aug 16, 2010 at 04:26:23PM +0200, Arnd Bergmann wrote:
> > Have you considered integrating the subsystem into the Posix clock/timer
> > framework?
>
> Yes, but see below.
>
> > I can't really tell from reading the source if th
On Mon, Aug 16, 2010 at 12:24 PM, john stultz wrote:
> On Mon, Aug 16, 2010 at 4:17 AM, Richard Cochran
> A few comments below
>
>> +** PTP user space API
>> +
>> + The class driver creates a character device for each registered PTP
>> + clock. User space programs may control the clock usi
On Mon, Aug 16, 2010 at 4:17 AM, Richard Cochran
wrote:
> This patch adds an infrastructure for hardware clocks that implement
> IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
> registration method to particular hardware clock drivers. Each clock is
> exposed to user space a
On Mon, Aug 16, 2010 at 04:26:23PM +0200, Arnd Bergmann wrote:
> Have you considered integrating the subsystem into the Posix clock/timer
> framework?
Yes, but see below.
> I can't really tell from reading the source if this is possible or
> not, but my feeling is that if it can be done, that wo
On Monday 16 August 2010, Richard Cochran wrote:
> This patch adds an infrastructure for hardware clocks that implement
> IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
> registration method to particular hardware clock drivers. Each clock is
> exposed to user space as a char
This patch adds an infrastructure for hardware clocks that implement
IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
registration method to particular hardware clock drivers. Each clock is
exposed to user space as a character device with ioctls that allow tuning
of the PTP clo
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