Adar Dembo has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/15171 )

Change subject: [clock] ntp_gettime(): STA_NANO bites again
......................................................................


Patch Set 1:

(1 comment)

Would be nice to think about how we could test this. Seems hard without mocking 
the results of whatever "get time" system call we end up using.

http://gerrit.cloudera.org:8080/#/c/15171/1//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/15171/1//COMMIT_MSG@9
PS1, Line 9: The issue fixed once in 10f6164b1217e0299bcfedc061d2c57581c389bd
           : was reintroduced again in e72208436.  And this patch addresses it
           : once again.
So here's ntp_gettime() implementation in glibc:

  int
  ntp_gettime (struct ntptimeval *ntv)
  {
    struct timex tntx;
    int result;

    tntx.modes = 0;
    result = __adjtimex (&tntx);
    ntv->time = tntx.time;
    ntv->maxerror = tntx.maxerror;
    ntv->esterror = tntx.esterror;
    return result;
  }

And __adjtimex() is the adjtimex/ntp_adjtime system call.

So the problem is that ntp_gettime() does not convert ntv->time using the 
presence of STA_NANO in tntx.status, right? How is that useful behavior? Seems 
like it makes the function completely unusable.

Could you update the commit description with a bit more color as to what's 
actually going on? When I first looked at the patch I didn't understand _why_ 
we shouldn't use ntp_gettime() on Linux.



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Id171b6fea2274d32a35c6173bab9996b36c0c4f6
Gerrit-Change-Number: 15171
Gerrit-PatchSet: 1
Gerrit-Owner: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Adar Dembo <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Volodymyr Verovkin <[email protected]>
Gerrit-Comment-Date: Thu, 06 Feb 2020 04:31:05 +0000
Gerrit-HasComments: Yes

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