* Re: ptp
[not found] <d1b2b740-8cc6-bf4a-722b-7b323fb0c7c0@cisco.com>
@ 2016-09-07 20:48 ` Richard Cochran
2016-09-07 20:55 ` ptp Daniel Walker
0 siblings, 1 reply; 3+ messages in thread
From: Richard Cochran @ 2016-09-07 20:48 UTC (permalink / raw)
To: Daniel Walker
Cc: netdev@vger.kernel.org, xe-kernel@external.cisco.com,
Shabeena Shabeena -X (sshabeen - ARICENT TECHNOLOGIES MAURIITIUS LIMITED at Cisco)
On Wed, Sep 07, 2016 at 01:40:59PM -0700, Daniel Walker wrote:
> There is a test (below) , which prevents negative nanosecond updates. The
> code below would force a negative update to always return more than
> NSEC_PER_SEC. It should be using abs() instead which would return the value
> desired.
No. This:
/*
* The value of a timeval is the sum of its fields, but the
* field tv_usec must always be non-negative.
*/
HTH,
Richard
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: ptp
2016-09-07 20:48 ` ptp Richard Cochran
@ 2016-09-07 20:55 ` Daniel Walker
2016-09-07 21:12 ` ptp Richard Cochran
0 siblings, 1 reply; 3+ messages in thread
From: Daniel Walker @ 2016-09-07 20:55 UTC (permalink / raw)
To: Richard Cochran
Cc: netdev@vger.kernel.org, xe-kernel@external.cisco.com,
Shabeena Shabeena -X (sshabeen - ARICENT TECHNOLOGIES MAURIITIUS LIMITED at Cisco)
On 09/07/2016 01:48 PM, Richard Cochran wrote:
> On Wed, Sep 07, 2016 at 01:40:59PM -0700, Daniel Walker wrote:
>> There is a test (below) , which prevents negative nanosecond updates. The
>> code below would force a negative update to always return more than
>> NSEC_PER_SEC. It should be using abs() instead which would return the value
>> desired.
> No. This:
>
> /*
> * The value of a timeval is the sum of its fields, but the
> * field tv_usec must always be non-negative.
> */
>
> HTH,
> Richard
So the code only allows second granularity negative updates, or the
seconds component is the only part which needs to actually be negative ?
Daniel
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: ptp
2016-09-07 20:55 ` ptp Daniel Walker
@ 2016-09-07 21:12 ` Richard Cochran
0 siblings, 0 replies; 3+ messages in thread
From: Richard Cochran @ 2016-09-07 21:12 UTC (permalink / raw)
To: Daniel Walker
Cc: netdev@vger.kernel.org, xe-kernel@external.cisco.com,
Shabeena Shabeena -X (sshabeen - ARICENT TECHNOLOGIES MAURIITIUS LIMITED at Cisco)
On Wed, Sep 07, 2016 at 01:55:19PM -0700, Daniel Walker wrote:
> So the code only allows second granularity negative updates,
No.
> or the seconds
> component is the only part which needs to actually be negative ?
Yes.
See the function, clockadj_step, in linuxptp/clockadj.c for a working
user space example.
Thanks,
Richard
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-09-07 21:12 UTC | newest]
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[not found] <d1b2b740-8cc6-bf4a-722b-7b323fb0c7c0@cisco.com>
2016-09-07 20:48 ` ptp Richard Cochran
2016-09-07 20:55 ` ptp Daniel Walker
2016-09-07 21:12 ` ptp Richard Cochran
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