Messages in this thread | | | From | Alexander Shishkin <> | Subject | Re: [PATCH v1 4/5] perf: Introduce address range filtering | Date | Mon, 25 Apr 2016 19:14:08 +0300 |
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Peter Zijlstra <peterz@infradead.org> writes:
> On Fri, Apr 22, 2016 at 07:19:11PM +0300, Alexander Shishkin wrote: >> +/* >> + * Address range filtering: limiting the data to certain >> + * instruction address ranges. Filters are ioctl()ed to us from >> + * userspace as ascii strings. >> + * >> + * Filter string format: >> + * >> + * ACTION SOURCE:RANGE_SPEC >> + * where ACTION is one of the >> + * * "filter": limit the trace to this region >> + * * "start": start tracing from this address >> + * * "stop": stop tracing at this address/region; >> + * SOURCE is either "file" or "kernel" >> + * RANGE_SPEC is >> + * * for "kernel": <start address>[/<size>] >> + * * for "file": <start address>[/<size>]@</path/to/object/file> > > SOURCE seems entirely redundant
In the current state, yes, but if we wanted dedicated support for kernel modules in filter definitions, it may come useful.
>> + * >> + * if <size> is not specified, the range is treated as a single address. > > single instruction, right?
Yes, hitting that instruction will trigger tracing to start. PT doesn't do this at the moment, but Coresight ETMs/PTMs do.
Regards, -- Alex
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