On Mon, Jan 07, 2019 at 04:27:27PM +0000, Andrew Murray wrote:
> For drivers that do not support context exclusion let's advertise the
> PERF_PMU_CAP_NOEXCLUDE capability. This ensures that perf will
> prevent us from handling events where any exclusion flags are set.
> Let's also remove the now unnecessary check for exclusion flags.
>
> Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
> ---
> arch/x86/events/amd/ibs.c | 13 +------------
> arch/x86/events/amd/power.c | 10 ++--------
> arch/x86/events/intel/cstate.c | 12 +++---------
> arch/x86/events/intel/rapl.c | 9 ++-------
> arch/x86/events/intel/uncore_snb.c | 9 ++-------
> arch/x86/events/msr.c | 10 ++--------
> 6 files changed, 12 insertions(+), 51 deletions(-)
You (correctly) don't add CAP_NO_EXCLUDE to the main x86 pmu code, but
then you also don't check if it handles all the various exclude options
correctly/consistently.
Now; I must admit that that is a bit of a maze, but I think we can at
least add exclude_idle and exclude_hv fails in there, nothing uses those
afaict.
On the various exclude options; they are as follows (IIUC):
- exclude_guest: we're a HV/host-kernel and we don't want the counter
to run when we run a guest context.
- exclude_host: we're a HV/host-kernel and we don't want the counter
to run when we run in host context.
- exclude_hv: we're a guest and don't want the counter to run in HV
context.
Now, KVM always implies exclude_hv afaict (for guests), I'm not sure
what, if anything Xen does on x86 (IIRC Brendan Gregg once said perf
works on Xen) -- nor quite sure who to ask, Boris, Jeurgen?
