Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [RFC v2 0/6] x86: dynamic indirect branch promotion | Date | Thu, 03 Jan 2019 14:18:15 -0800 |
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Nadav Amit <namit@vmware.com> writes: > > - Do we use periodic learning or not? Josh suggested to reconfigure the > branches whenever a new target is found. However, I do not know at > this time how to do learning efficiently, without making learning much > more expensive.
FWIW frequent patching will likely completely break perf Processor Trace decoding, which needs a somewhat stable kernel text image to decode the traces generated by the CPU. Right now it relies on kcore dumped after the trace usually being stable because jumplabel changes happen only infrequently. But if you start patching frequently this assumption will break.
You would either need a way to turn this off, or provide updates for every change to the trace, so that the decoder can keep track.
-Andi
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