PC Processors

[czg]

Recently I wanted to use perf to view cache miss state of codes. Then I refered to my [cpu PPR doc] ( my cpu amd ryzen r7 4800h can be [checked here], it is Renoir design.) and part of the [linux source codes]. But it seems that they all not offer detailed information about "Miscellaneous events" list. The doc says in `PMCx060` description:

> Bits Description
> 0 Group2. Read-write. Reset: 0. Miscellaneous events covered in more detail by Core::X86::Pmc::Core::L2RequestG2 (PMCx061).

Then I read the [OSRR(Open-Source Register Reference) for 17h family] (although the file name is "... Models 00h-2Fh"), it says about `PMCx060`:

> 0 OtherRequests. Read-write. Reset: 0. Events covered by Core::X86::Pmc::Core::L2RequestG2.

But about `PMCx061` it says:
> 7 Group1. Read-write. Reset: 0. All Group 1 commands not in **unit0**.

Amd seems to not offer 17h family BIOS and KernelDeveloper’s Guide (BKDG) doc, the latest is [16h][5]. And it isn't compatible because it only has one `L2IPMCx060` and says "L2IPMCx060 Command Related to Victim Buffers".

Q: What does "unit0" mean?

Does it mean that unitmask is 0? If so, it seems weird.

[BillyFeltrop]

In the context you provided, "unit0" refers to a specific unit within the AMD processor that is responsible for certain performance monitoring functions. It is used to differentiate between different groups or categories of events that can be monitored using performance counters.

In the description you mentioned, it states that events covered by "Core::X86::Pmc::Core::L2RequestG2" are not included in "unit0" for the PMCx061 register. This means that the specific events related to Group 1 commands mentioned in PMCx061 are not part of the unit0 category.

Unfortunately, without more specific information or documentation from AMD, it is difficult to provide a more detailed explanation of what "unit0" precisely refers to in this context.

[czg]

Thanks for the reply.

I found the PPR p163 says "UnitMask" "Reset: 00h". Does it mean that unit0 is reset state and monitors nothing at all?