[Bug 1812313] Re: SKX Gold 6129, Platinum 8168 cpu frequency throttling issue during the benchmark

[Adam Conrad]

** Also affects: glibc (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: glibc
       Status: New => Fix Released

** Also affects: glibc (Ubuntu Xenial)
   Importance: Undecided
       Status: New

** Changed in: glibc (Ubuntu)
       Status: New => Fix Released

** Changed in: glibc (Ubuntu Xenial)
     Assignee: (unassigned) => Adam Conrad (adconrad)

** Changed in: glibc (Ubuntu Xenial)
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/1812313

Title:
  SKX Gold 6129,Platinum 8168  cpu frequency throttling issue during the
  benchmark

Status in GLibC:
  Fix Released
Status in intel:
  Fix Committed
Status in glibc package in Ubuntu:
  Fix Released
Status in glibc source package in Xenial:
  In Progress

Bug description:
  Description:

  This is a known issue. Glibc fix is available:
  glibc 2.23 branch more than a year ago:
  https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/release/2.23/master
  The specific commit for glibc 2.23 is
  https://sourceware.org/git/?p=glibc.git;a=commit;h=26d289bb92b6d1125536644f607c73617463477d

  
  History:
      in Ubuntu 16.04.5 ,If the benchmark tools is dynamic linked, and in the main loop, there are external function call to the dynamic lib, like dhrystone, whetstone, sysbench… During the benchmark running, CPU core max frequency is always 2.2Ghz(Gold 6129 , max turbo should be 3.3Ghz). Even the test is single thread test, we got the same result. In our lab, we found with our Gold 6129 chipset, cpu is always at 1.5Ghz while benchmarking. 
      In Ubuntu 18.04.1 (glibc 2.27),everything works fine. No freq limit. Try to upgrade the glibc on Ubuntu 16.04.5 from 2.23 to 2.27, the Gold 6129 works fine, can reach 3.3Ghz. There is the same issue on Platinum 8168, on Ubuntu 16.04.5(glibc2.23),  cpu max frequency during benchmark is about 3Ghz（Platinum 8168 ,1~2 cores max turbo should be 3.7Ghz). Xeon Gold 6129 and Platinum 8168 are major Skylake platform

  Target Release: 16.04.5

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