Hi,
On Thu, Jun 8, 2017 at 1:15 AM, Peter Zijlstra <[email protected]> wrote:
>
> On Wed, Jun 07, 2017 at 04:22:24PM -0700, Andi Kleen wrote:
>
> > diff --git a/include/uapi/linux/perf_event.h
> > b/include/uapi/linux/perf_event.h
> > index b1c0b187acfe..95daade294d7 100644
> > --- a/include/uapi/linux/perf_event.h
> > +++ b/include/uapi/linux/perf_event.h
> > @@ -931,14 +931,18 @@ union perf_mem_data_src {
> > mem_snoop:5, /* snoop mode */
> > mem_lock:2, /* lock instr */
> > mem_dtlb:7, /* tlb access */
> > - mem_rsvd:31;
> > + mem_lvlx:8, /* memory hierarchy level, ext */
> > + mem_snoopx:2, /* snoop mode, ext */
> > + mem_rsvd:21;
> > };
> > };
> > #elif defined(__BIG_ENDIAN_BITFIELD)
> > union perf_mem_data_src {
> > __u64 val;
> > struct {
> > - __u64 mem_rsvd:31,
> > + __u64 mem_rsvd:21,
> > + mem_snoopx:2, /* snoop mode, ext */
> > + mem_lvlx:8, /* memory hierarchy level, ext */
> > mem_dtlb:7, /* tlb access */
> > mem_lock:2, /* lock instr */
> > mem_snoop:5, /* snoop mode */
>
> So one thing we could do is add a mem_hops field and always set that,
> even for the old stuff. The old stuff will not know about that field and
> ignore the bits, but new stuff will then not need as many LVL bits.
>
That would be better than lvlx I think. I am guessing you're suggesting
an integer count here and not a bitmask. Right? Then I wonder why it
would need 8 bits or 255 possible levels!
> Of course, we then get into the problem of how many bits of hops we
> need.. Power guys ?
>
> > @@ -975,6 +979,16 @@ union perf_mem_data_src {
> > #define PERF_MEM_LVL_UNC 0x2000 /* Uncached memory */
> > #define PERF_MEM_LVL_SHIFT 5
> >
> > +#define PERF_MEM_LVLX_L4 0x01 /* L4 */
> > +#define PERF_MEM_LVLX_REM_L4 0x02 /* Remote L4 */
> > +#define PERF_MEM_LVLX_REM_RAM 0x04 /* Remote Ram, unknown hops */
> > +#define PERF_MEM_LVLX_PMEM 0x08 /* Persistent Memory */
> > +#define PERF_MEM_LVLX_REM_PMEM 0x10 /* Remote Persistent Memory */
> > +#define PERF_MEM_LVLX_REM_NA 0x20 /* Remote N/A level */
>
> Still wondering what the point of REM_NA is.. can you explain?
>
> > +/* 2 free */
> > +
> > +#define PERF_MEM_LVLX_SHIFT 33
> > +
> > /* snoop mode */
> > #define PERF_MEM_SNOOP_NA 0x01 /* not available */
> > #define PERF_MEM_SNOOP_NONE 0x02 /* no snoop */
> > @@ -983,6 +997,10 @@ union perf_mem_data_src {
> > #define PERF_MEM_SNOOP_HITM 0x10 /* snoop hit modified */
> > #define PERF_MEM_SNOOP_SHIFT 19
> >
> > +#define PERF_MEM_SNOOPX_FWD 0x01 /* forward */
> > +/* 1 free */
> > +#define PERF_MEM_SNOOPX_SHIFT 41
> > +
> > /* locked instruction */
> > #define PERF_MEM_LOCK_NA 0x01 /* not available */
> > #define PERF_MEM_LOCK_LOCKED 0x02 /* locked transaction */
> > --
> > 2.9.4
> >
