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perf-collect can't work #50

Answered by hilldani
shaileneF asked this question in Q&A
Jul 7, 2023 · 13 comments · 1 reply
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Yes there could be several reasons for this.

  1. If you're on ICX or later system then there is a new piece of hardware introduced specifically to collect topdown events. Its the fourth fixed register in the PMU (after cycles, instructions, and ref-cycles). So you'll need a newer perf to know about this
  2. If you're in a VM on ICX or later, most VM's forget to expose the topdown PMU register.
  3. If you're on CLX/SKX then most events got their support added in the following kernels. Some distro's backported further than others.
  4. If it's giving zero for the slots then its not supported. However some of the deeper level (L1 or L2) topdown metrics can actually legitimately give zero because the events …

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bug Something isn't working
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Converted from issue

This discussion was converted from issue #46 on August 15, 2023 19:03.