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Message-ID: <c79639cd5a4c4907b83e2f5df50bd2bc@APLEX07.dom1.jhuapl.edu> Date: Wed, 27 Jul 2016 21:15:23 +0000 From: "Woodford, Timothy W." <Timothy.Woodford@...apl.edu> To: "Avargil, Raanan" <raanan.avargil@...el.com>, Jarod Wilson <jarod@...hat.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Hall, Christopher S" <christopher.s.hall@...el.com> CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org> Subject: RE: [Intel-wired-lan] [PATCH net-next v3 1/2] e1000e: factor out systim sanitization >> This is prepatory work for an expanding list of adapter families that have occasional ~10 hour clock jumps when being used for PTP. Factor out the sanitization function and convert to using a feature (bug) flag, per suggestion from Jesse Brandeburg. >> >> Littering functional code with device-specific checks is much messier than simply checking a flag, and having device-specific init set flags as needed. >> There are probably a number of other cases in the e1000e code that could/should be converted similarly. > > Looks ok to me. > Adding Chris who asked what happens if we reach the max retry counter (E1000_MAX_82574_SYSTIM_REREAD)? > This counter is set to 50. > Can you, for testing purposes, decreased this value (or even set it to 0) and see what happens? I have one of the affected NICs. I inserted some test code into the module to check the value of i after the for loop inside the sanitize function exits to check how many iterations of the loop were being run. I ran a PTP test setup for a few hours with E1000_MAX_82574_SYSTIM_REREAD=50, and the maximum number was 5 iterations. It looks like setting E1000_MAX_82574_SYSTIM_REREAD to 0 will just disable the return value checking and will have the same results as disabling the sanitization function. I'll set the max retry counter to 1 and run an overnight test to see what happens. Tim Woodford
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