On Sat, May 27, 2017 at 12:38 AM, Ingo Molnar <[email protected]> wrote: > > * John Stultz <[email protected]> wrote: > >> As part of the Linaro Linux Kernel Functional Test (LKFT) >> effort, test failures from kselftest/timer's >> inconsistency-check were reported connected to >> CLOCK_MONOTONIC_RAW, on the HiKey platform. >> >> Digging in I found that an old issue with how sub-ns accounting >> is handled with the RAW time which was fixed long ago with the >> CLOCK_MONOTONIC/REALTIME ids, but missed with RAW time, was >> present. >> >> Additionally, running further tests, I uncovered an issue with >> how the clocksource read function is handled when clocksources >> are changed, which can cause crashes. >> >> Both of these issues have not been uncovered in x86 based >> testing due to x86 not using vDSO to accelerate >> CLOCK_MONOTONIC_RAW, combined with the HiKey's arch_timer >> clocksource being fast to access but incrementing slowly enough >> to get multiple reads using the same counter value (which helps >> uncover time handing issues), along with the fact that none of >> the x86 clocksources making use of the clocksource argument >> passed to the read function. >> >> This patchset addresses these two issues. > > AFAICS only the first two patches are fixes, the other two patches are > cleanups/simplifications that resulted out of the debugging effort, right?
Actually the first three are fixes (ARM64 still sees discontinuities until the vDSO is fixed), the last one is a cleanup. thanks -john
