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28 * Authors: Daniel Carvalho
31 #include "mem/cache/replacement_policies/brrip_rp.hh"
36 #include "base/logging.hh" // For fatal_if
37 #include "base/random.hh"
38 #include "params/BRRIPRP.hh"
40 BRRIPRP::BRRIPRP(const Params
*p
)
41 : BaseReplacementPolicy(p
),
42 maxRRPV(p
->max_RRPV
), hitPriority(p
->hit_priority
), btp(p
->btp
)
44 fatal_if(maxRRPV
<= 0, "max_RRPV should be greater than zero.\n");
48 BRRIPRP::invalidate(const std::shared_ptr
<ReplacementData
>& replacement_data
)
51 std::shared_ptr
<BRRIPReplData
> casted_replacement_data
=
52 std::static_pointer_cast
<BRRIPReplData
>(replacement_data
);
54 // Set RRPV to an invalid distance
55 casted_replacement_data
->rrpv
= maxRRPV
+ 1;
59 BRRIPRP::touch(const std::shared_ptr
<ReplacementData
>& replacement_data
) const
61 std::shared_ptr
<BRRIPReplData
> casted_replacement_data
=
62 std::static_pointer_cast
<BRRIPReplData
>(replacement_data
);
64 // Update RRPV if not 0 yet
65 // Every hit in HP mode makes the entry the last to be evicted, while
66 // in FP mode a hit makes the entry less likely to be evicted
68 casted_replacement_data
->rrpv
= 0;
69 } else if (casted_replacement_data
->rrpv
> 0) {
70 casted_replacement_data
->rrpv
--;
75 BRRIPRP::reset(const std::shared_ptr
<ReplacementData
>& replacement_data
) const
77 std::shared_ptr
<BRRIPReplData
> casted_replacement_data
=
78 std::static_pointer_cast
<BRRIPReplData
>(replacement_data
);
81 // Replacement data is inserted as "long re-reference" if lower than btp,
82 // "distant re-reference" otherwise
83 if (random_mt
.random
<unsigned>(1, 100) <= btp
) {
84 casted_replacement_data
->rrpv
= maxRRPV
-1;
86 casted_replacement_data
->rrpv
= maxRRPV
;
91 BRRIPRP::getVictim(const ReplacementCandidates
& candidates
) const
93 // There must be at least one replacement candidate
94 assert(candidates
.size() > 0);
96 // Use first candidate as dummy victim
97 ReplaceableEntry
* victim
= candidates
[0];
99 // Store victim->rrpv in a variable to improve code readability
100 int victim_RRPV
= std::static_pointer_cast
<BRRIPReplData
>(
101 victim
->replacementData
)->rrpv
;
103 // Visit all candidates to find victim
104 for (const auto& candidate
: candidates
) {
105 // Get candidate's rrpv
106 int candidate_RRPV
= std::static_pointer_cast
<BRRIPReplData
>(
107 candidate
->replacementData
)->rrpv
;
109 // Stop searching for victims if an invalid entry is found
110 if (candidate_RRPV
== maxRRPV
+ 1) {
112 // Update victim entry if necessary
113 } else if (candidate_RRPV
> victim_RRPV
) {
115 victim_RRPV
= candidate_RRPV
;
119 // Get difference of victim's RRPV to the highest possible RRPV in
120 // order to update the RRPV of all the other entries accordingly
121 int diff
= maxRRPV
- victim_RRPV
;
123 // No need to update RRPV if there is no difference
125 // Update RRPV of all candidates
126 for (const auto& candidate
: candidates
) {
127 std::static_pointer_cast
<BRRIPReplData
>(
128 candidate
->replacementData
)->rrpv
+= diff
;
135 std::shared_ptr
<ReplacementData
>
136 BRRIPRP::instantiateEntry()
138 return std::shared_ptr
<ReplacementData
>(new BRRIPReplData(maxRRPV
));
142 BRRIPRPParams::create()
144 return new BRRIPRP(this);