tree 1c9955959fcb9d6add0e2593308ad9e0fa789123
parent eb573e746b9d4f0921dcb2449be3df41dae3caea
author Michael Petlan <mpetlan@redhat.com> 1575822056 +0100
committer Arnaldo Carvalho de Melo <acme@redhat.com> 1576078094 -0300

perf header: Fix false warning when there are no duplicate cache entries

Before this patch, perf expected that there might be NPROC*4 unique
cache entries at max, however, it also expected that some of them would
be shared and/or of the same size, thus the final number of entries
would be reduced to be lower than NPROC*4. In case the number of entries
hadn't been reduced (was NPROC*4), the warning was printed.

However, some systems might have unusual cache topology, such as the
following two-processor KVM guest:

	cpu  level  shared_cpu_list  size
	  0     1         0           32K
	  0     1         0           64K
	  0     2         0           512K
	  0     3         0           8192K
	  1     1         1           32K
	  1     1         1           64K
	  1     2         1           512K
	  1     3         1           8192K

This KVM guest has 8 (NPROC*4) unique cache entries, which used to make
perf printing the message, although there actually aren't "way too many
cpu caches".

v2: Removing unused argument.

v3: Unifying the way we obtain number of cpus.

v4: Removed '& UINT_MAX' construct which is redundant.

Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
LPU-Reference: 20191208162056.20772-1-mpetlan@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>