Messages in this thread | | | Date | Thu, 3 Dec 2009 13:01:30 +0100 | From | Rodolfo Giometti <> | Subject | Re: [PATCH 09/11] pps: low level IRQ timestamps recording. |
| |
On Wed, Dec 02, 2009 at 04:10:44PM -0800, H. Peter Anvin wrote: > On 12/02/2009 09:18 AM, Rodolfo Giometti wrote: > > Add low level IRQ timestamps recording for x86 (32 and 64 bits) > > platforms and enable UART clients in order to use it. > > > > This improves PPS precision. :) > > It also invokes getnstimeofday on every single interrupt, including ones > which have absolutely nothing to do with the PPS, and are potentially > high volume. getnstimeofday can be a fairly expensive operation, > especially if the best available clock is away from the CPU, or it > requires extensive arithmetic in order to normalize the clock value...
I see, that's why I propose my patches to you: in order to have some feedbacks for better solutions. :)
Can I add a IRQF_TIMESTAMP in order to ask to the system to record irq timestamps for particular irq lines? The problem is that I cannot set that flag at irq_register() time but I have to do it later... it can be a problem?
Ciao,
Rodolfo
--
GNU/Linux Solutions e-mail: giometti@enneenne.com Linux Device Driver giometti@linux.it Embedded Systems phone: +39 349 2432127 UNIX programming skype: rodolfo.giometti Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it
| |