AMD 3200 Revision History - Page 75

Instruction-Based, Sampling, Inaccurate

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48063 Rev. 3.18 October 2012 Revision Guide for AMD Family 15h Models 00h-0Fh Processors 717 Instruction-Based Sampling May Be Inaccurate Description The processor may experience sampling inaccuracies when Instruction-Based Sampling (IBS) is enabled in the following cases: • When IBS Op Data 3 Register[IbsDcMiss] (MSRC001_1037[7]) is 0b, IBS Op Data 3 Register[IbsDcMabHit] (MSRC001_1037[16])] should always be 0b. However, the processor may incorrectly set IbsDcMabHit. • When the processor samples an instruction that is altering the CS_BASE value, the IbsOpRip reported in IBS Op Logical Address (MSRC001_1034) may be determined using an incorrect CS_BASE. • In rare instances, a tagged branch may set an inaccurate value in IBS Branch Target Address Register (MSRC001_103B). Potential Effect on System Inaccuracies in performance monitoring software may be experienced. Suggested Workaround The following workarounds can be used for the above issues: • Performance monitoring software should treat IBS Op Data 3 Register[IbsDcMabHit] (MSRC001_1037[16]) as 0b when MSRC001_1037[7] is 0b. • No workaround is necessary for IbsOpRip when CS_BASE is zero. CS_BASE is normally zero in commercially available software. • Performance monitoring software should not rely on the value in MSRC001_103B (IbsBrTarget). Fix Planned Yes Product Errata 75

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717
Instruction-Based
Sampling
May
Be
Inaccurate
Description
The
processor
may
experience
sampling
inaccuracies
when
Instruction-Based
Sampling
(
IBS
is
enabled
in
the
following
cases
:
When
IBS
Op
Data
3
Register
[
IbsDcMiss
] (
MSRC
001_1037[7]
is
0
b
,
IBS
Op
Data
3
Register
[
IbsDcMabHit
] (
MSRC
001_1037[16] ]
should
always
be
0
b
.
However
,
the
processor
may
incorrectly
set
IbsDcMabHit
.
When
the
processor
samples
an
instruction
that
is
altering
the
CS
_
BASE
value
,
the
IbsOpRip
reported
in
IBS
Op
Logical
Address
(
MSRC
001_1034
may
be
determined
using
an
incorrect
CS
_
BASE
.
In
rare
instances
,
a
tagged
branch
may
set
an
inaccurate
value
in
IBS
Branch
Target
Address
Register
(
MSRC
001_103
B
.
Potential
Effect
on
System
Inaccuracies
in
performance
monitoring
software
may
be
experienced
.
Suggested
Workaround
The
following
workarounds
can
be
used
for
the
above
issues
:
Performance
monitoring
software
should
treat
IBS
Op
Data
3
Register
[
IbsDcMabHit
] (
MSRC
001_1037[16]
as
0
b
when
MSRC
001_1037[7]
is
0
b
.
No
workaround
is
necessary
for
IbsOpRip
when
CS
_
BASE
is
zero
.
CS
_
BASE
is
normally
zero
in
commercially
available
software
.
Performance
monitoring
software
should
not
rely
on
the
value
in
MSRC
001_103
B
(
IbsBrTarget
.
Fix
Planned
Yes
48063
Rev
. 3.18
October
2012
Revision
Guide
for
AMD
Family
15
h
Models
00
h-
0
Fh
Processors
Product
Errata
75