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Re: Sporadic failures of rt/tst-cputimer1 on ppc64le (POWER8 hardware)?
- From: "Tulio Magno Quites Machado Filho" <tuliom at linux dot vnet dot ibm dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>, Carlos Eduardo Seo <cseo at linux dot vnet dot ibm dot com>
- Cc:
- Date: Fri, 29 Apr 2016 17:58:20 -0300
- Subject: Re: Sporadic failures of rt/tst-cputimer1 on ppc64le (POWER8 hardware)?
- Authentication-results: sourceware.org; auth=none
- References: <5723AF52 dot 3000206 at redhat dot com>
Carlos O'Donell <carlos@redhat.com> writes:
> [ text/plain ]
> On ppc64le I see a sporadic failure in rt/tst-cputimer1:
>
> clock_gettime returned timespec = { 0, 405994 }
> clock_getres returned timespec = { 0, 1 }
> *** timer sig1 invoked too soon: 0.400715218 instead of expected 0.400761014
> *** timer sig2 invoked too soon: 0.500710982 instead of expected 0.500761014
>
> The kernel says the clock resolution is 1 nanosecond, that seems exceedingly
> prcise.
I believe it has been that way since http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=597bc5c00b666fe123abb0af64f6e86f7ab72a90
>
> The kernel invokes the signal ~46 micorseconds too early, which is not
> allowed by the tests. You can invoke late, but not early.
>
> Have either of you seen this before?
I noticed this for the first time earlier today on a Linux 3.13 box, but I
still wasn't able to reproduce it on another server with a newer kernel.
I suspect it might be related to another failure on rt/tst-cputimer3 which I
can reproduce only on the same server that rt/tst-cputimer1 failed today.
Notice that I'm able to reproduce rt/tst-cputimer3 on glibc 2.23, while
rt/tst-cputimer1 failed with 2.24.
I wonder if these failures are related to this:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6e998916dfe327e785e7c2447959b2c1a3ea4930
Where did you reproduce it?
--
Tulio Magno