694
IBS
Sampling
of
Instruction
Fetches
May
Be
Uneven
Description
Instructions
selected
for
instruction-based
sampling
(
IBS
)
of
fetch
performance
(
Fetch
Control
[
IbsFetchEn
],
MSRC
001_1030[48] = 1
b
)
may
be
sampled
unevenly
when
the
instruction
fetch
stream
is
redirected
(
e
.
g
.,
due
to
a
branch
taken
).
Potential
Effect
on
System
Performance
monitoring
software
may
not
receive
even
,
unbiased
IBS
sampling
of
the
instruction
fetch
stream
.
However
,
IBS
can
still
be
used
effectively
for
identifying
performance
issues
associated
with
specific
instructions
.
The
sampling
bias
makes
IBS
less
effective
for
measuring
the
statistical
distribution
of
operations
and
events
.
Suggested
Workaround
None
.
Fix
Planned
No
fix
planned
48063
Rev
. 3.18
October
2012
Revision
Guide
for
AMD
Family
15
h
Models
00
h-
0
Fh
Processors
Product
Errata
67