> -----Original Message----- > From: Miroslav Lichvar [mailto:mlich...@redhat.com] > Sent: Friday, October 05, 2018 1:37 AM > To: Keller, Jacob E <jacob.e.kel...@intel.com> > Cc: linuxptp-devel@lists.sourceforge.net; Richard Cochran > (richardcoch...@gmail.com) <richardcoch...@gmail.com> > Subject: Re: measuring accuracy/precision of software timestamping when using > ptp4l > > On Thu, Oct 04, 2018 at 03:38:41PM +0000, Keller, Jacob E wrote: > > > On Wed, Oct 03, 2018 at 09:39:14PM +0000, Keller, Jacob E wrote: > > > > I'm investigating a potential software driver bug in which a driver > > > > calls > > > skb_tx_timestamp earlier than necessary, and I want to gather some > informational > > > data to indicate whether or not moving the function to a later point in > > > the driver > tx/rx > > > path would actually improve the accuracy/precision. > > > > > > You mean the TX path only? An RX timestamp should be captured as soon > > > as possible. > > > > > > > This is Tx path, because that's the bit controlled by the drivers. AFAIK > > the Rx > timestamping is done by the stack when the driver pushes the SKB up, right? > > Yes, I think that's how it's supposed to work, but I'm not sure if a > driver couldn't put there a more accurate timestamp earlier. > > Ideally, the RX timestamp would be taken right after the interrupt (if > there was one), like with PPS for instance.
I'm sure it's technically possible, but I don't know if there is an available kernel interface for doing so. Thanks, Jake > > -- > Miroslav Lichvar _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
