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SubjectRe: [PATCH] perf intel-pt: Add a config for max loops without consuming a packet

On 7/1/2021 10:51 AM, Adrian Hunter wrote:
> The Intel PT decoder limits the number of unconditional branches (e.g.
> jmps) decoded without consuming any trace packets. Generally, a loop
> needs a conditional branch which generates a TNT packet, whereas a
> "ret" instruction will generate a TIP or TNT packet. So exceeding
> the limit is assumed to be a never-ending loop, which can happen if
> there has been a decoding error putting the decoder at the wrong place in
> the code.
> Up until now, the limit of 10000 has been enough but some analytic
> purposes have been reported to exceed that.
> Increase the limit to 100000, and make it configurable via perf config
> intel-pt.max-loops. Also amend the "Never-ending loop" message to
> mention the configuration entry.
> Signed-off-by: Adrian Hunter <>

Thanks. That is useful.

Reviewed-by: Andi Kleen <>


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