vm.pmap.pcid_enabled="0" seems to eliminate Java/Jenkins crashing problems in FBSD 10

[Craig Rodrigues]

On Fri, Feb 21, 2014 at 3:13 PM, Jung-uk Kim <jkim at freebsd.org> wrote:

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> On 2014-02-21 17:54:58 -0500, Attilio Rao wrote:
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> No, it is enabled by default on all 10+ AFAICT.
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> http://svnweb.freebsd.org/base/head/sys/amd64/amd64/pmap.c?annotate=261781#l370
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> http://svnweb.freebsd.org/base/stable/10/sys/amd64/amd64/pmap.c?annotate=260467#l370
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> http://svnweb.freebsd.org/base/releng/10.0/sys/amd64/amd64/pmap.c?annotate=259065#l370
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Yes, I looked at the code with Xin Li,
and Xin showed me that the default behavior of the code is
to examine the capabilities of the CPU, and if the PCID feature
is available, it then sets vm.pmap.pcid_enabled=1.

So my next question is:  where is the bug?

If it:
  -> bug in code implementatino of pcid?
  -> bug in FreeBSD VM?
  -> bug in microcode of CPU?

For now I can work around this by turning the feature off,
but it would be nice to fix this, since a lot of effort has been done to
improve performance.
--
Craig