On Tue, Jul 08, 2014 at 09:49:40AM -0700, [email protected] wrote: > --- a/arch/x86/kernel/cpu/perf_event.h > +++ b/arch/x86/kernel/cpu/perf_event.h > @@ -464,6 +464,12 @@ struct x86_pmu { > */ > struct extra_reg *extra_regs; > unsigned int er_flags; > + /* > + * EXTRA REG MSR can be accessed > + * The extra registers are completely unrelated to each other. > + * So it needs a flag for each extra register. > + */ > + bool extra_msr_access[EXTRA_REG_MAX]; > > /* > * Intel host/guest support (KVM)
# pahole -C extra_reg arch/x86/kernel/cpu/perf_event_intel.o
struct extra_reg {
unsigned int event; /* 0 4 */
unsigned int msr; /* 4 4 */
u64 config_mask; /* 8 8 */
u64 valid_mask; /* 16 8 */
int idx; /* 24 4 */
/* size: 32, cachelines: 1, members: 5 */
/* padding: 4 */
/* last cacheline: 32 bytes */
};
There's still 4 empty bytes at the tail of extra_reg itself; would it
make sense to store the availability of the reg in there?
After all; the place we use it (x86_pmu_extra_regs) already has the
pointer to the structure.
pgpX9t55zaLgb.pgp
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