linux_dsm_epyc7002/arch/x86/include
Kim Phillips 8b0bed7d41 perf/x86/amd/ibs: Support 27-bit extended Op/cycle counter
IBS hardware with the OpCntExt feature gets a 7-bit wider internal
counter.  Both the maximum and current count bitfields in the
IBS_OP_CTL register are extended to support reading and writing it.

No changes are necessary to the driver for handling the extra
contiguous current count bits (IbsOpCurCnt), as the driver already
passes through 32 bits of that field.  However, the driver has to do
some extra bit manipulation when converting from a period to the
non-contiguous (although conveniently aligned) extra bits in the
IbsOpMaxCnt bitfield.

This decreases IBS Op interrupt overhead when the period is over
1,048,560 (0xffff0), which would previously activate the driver's
software counter.  That threshold is now 134,217,712 (0x7fffff0).

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200908214740.18097-7-kim.phillips@amd.com
2020-09-10 11:19:36 +02:00
..
asm perf/x86/amd/ibs: Support 27-bit extended Op/cycle counter 2020-09-10 11:19:36 +02:00
uapi/asm Support for FSGSBASE. Almost 5 years after the first RFC to support it, 2020-08-04 21:16:22 -07:00