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As a FUD reduction measure, this patch implements 2-way parallel
counter collection. Synthetic stat component counter pairs run at the
same time. Running two counters (of any kind) at the same time
naturally reduces the aggregate time required by an approximate
factor-of-2, depending on whether an even or odd number of stats have
been requested.
I don't completely buy the argument that computing synthetic stats
such as instructions-per-clock will be inaccurate if component counter
values are collected sequentially. Given uniform traffic pattern, it
must make no difference.
As the collection interval increases, the difference between serial
and parallel component counter collection will approach zero, see also
the Central Limit theorem.
Change-Id: I36ebdcf125e8882cca8a1929ec58f17fba1ad8f1
Signed-off-by: Dave Barach <dave@barachs.net>
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Built a tool to chew up https://download.01.org/perfmon/mapfile.csv,
and output a table in this format:
typedef struct {
u8 model;
u8 stepping;
u8 has_stepping;
char *filename;
} file_by_model_and_stepping_t;
static const file_by_model_and_stepping_t fms_table [] =
{
/* model, stepping, stepping valid, file */
{ 0x2E, 0x0, 0, "NehalemEX_core_V2.json" },
{ 0x1E, 0x0, 0, "NehalemEP_core_V2.json" },
<snip>
{ 0x55, 0x5, 1, "cascadelakex_core_v1.00.json" },
{ 0x55, 0x6, 1, "cascadelakex_core_v1.00.json" },
{ 0x55, 0x7, 1, "cascadelakex_core_v1.00.json" },
<snip>
Change-Id: Ie0e8a7e851799e9d060b966047745039c066ec7b
Signed-off-by: Dave Barach <dave@barachs.net>
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Dave Barach
Paul Vinciguerra