RE: [PATCH RFC 00/10] counter read during perf sampling

From: Liang, Kan
Date: Mon Sep 28 2015 - 11:11:29 EST

> > >
> > > hum, how the --counter-read-interval data displayed then? it's not
> > > single number right?
> > >
> > No matter which way we choose, I think the output should be similar.
> >
> > As my original design, perf only output every --counter-read-interval
> > data in perf report -D.
> > For tui and stdio, it only output the aggregate number. So, yes, single
> number.
> >
> > I think it should be enough. In tui/stdio, perf gives user a roughly
> > image by the total number during the whole sampling process. If they
> > want details, they can check by report -D.
> > Considering the interval is only 10ms, if perf output everything in
> > tui/stdio, the output is too huge.
> what is the reason to read the counter multiple times

For doing sophisticated memory bandwidth analysis, it requires 10-20ms
interval to read uncore counter.

> if you display only
> single number at the end? overflow issues?

Display issue. If we set 10ms interval and do perf record stat for 10s, there
will be 1000 records per cpu. For a system with 64 cpu, there will be 64,000
number. We cannot show all of them in tui/stdio mode.
I think it's better to only show the total number in tui/stdio mode.
If the user want to do sophisticated analysis, they can use -D to dump all


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at