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mem-ruby: Writeback CHI UD_RU line at local evict

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In Ruby CHI protocol UD_RU state means the line is in UD state in
the local cache and the upstream may have it in UD or UC state.
In the previous implementation UD_RU line was just dropped without
WriteBack which can cause loss of dirty data when the upstream has it
in UC state.
This commit fixes it by performing WriteBack when evciting UD_RU line.

Change-Id: I1db9b4f95cc576e71dcef38b01de24775df514ba
This commit is contained in:
Minje Jun
2024-01-21 16:14:53 +09:00
committed by Minje Jun
parent 4aecf9d35c
commit e141d9e4d0
2 changed files with 9 additions and 9 deletions
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8
src/mem/ruby/protocol/chi/CHI-cache-funcs.sm
View File

@@ -892,10 +892,10 @@ void copyCacheAndDir(CacheEntry cache_entry, DirEntry dir_entry,
if (is_valid(cache_entry) &&
((initialState == State:UD) || (initialState == State:SD) ||
(initialState == State:UC) || (initialState == State:SC) ||
(initialState == State:UD_RSC) || (initialState == State:SD_RSC) ||
(initialState == State:UC_RSC) || (initialState == State:SC_RSC) ||
(initialState == State:UD_RSD) || (initialState == State:SD_RSD) ||
(initialState == State:UD_T))) {
(initialState == State:UD_RU) || (initialState == State:UD_RSC) ||
(initialState == State:SD_RSC) || (initialState == State:UC_RSC) ||
(initialState == State:SC_RSC) || (initialState == State:UD_RSD) ||
(initialState == State:SD_RSD) || (initialState == State:UD_T))) {
tbe.dataBlk := cache_entry.DataBlk;
tbe.dataBlkValid.fillMask();
tbe.dataValid := true;

10
src/mem/ruby/protocol/chi/CHI-cache-transitions.sm
View File

@@ -710,10 +710,10 @@ transition({UD_RSC, UC_RSC, SC_RSC, SD_RSC, UD, RU, RSD, RUSD, RUSC, UD_RSD, SD_
// Cache Replacement
// When in UD_RU,UC_RU,UD_RSD,SD_RSD we also just drop the line since an upstream
// When in UC_RU,UD_RSD,SD_RSD we also just drop the line since an upstream
// cache has an up-to-data line that it will either WriteBack or WriteEvict
transition({SC,UC,SC_RSC,UC_RSC,
UD_RU,UC_RU,UD_RSD,SD_RSD}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
UC_RU,UD_RSD,SD_RSD}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
Initiate_Replacement;
Initiate_Replacement_JustDrop;
Profile_Eviction;
@@ -722,7 +722,7 @@ transition({SC,UC,SC_RSC,UC_RSC,
ProcessNextState;
}
transition({UD,SD,UD_RSC,SD_RSC}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
transition({UD,SD,UD_RU,UD_RSC,SD_RSC}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
Initiate_Replacement;
Initiate_Replacement_WB;
Profile_Eviction;
@@ -749,7 +749,7 @@ transition({UD,SD,UC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
ProcessNextState;
}
transition({UD_RU,UC_RU,UD_RSD,SD_RSD,SC_RSC,UC_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
transition({UC_RU,UD_RSD,SD_RSD,SC_RSC,UC_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
Initiate_Replacement;
Initiate_Replacement_JustDrop;
Profile_Eviction;
@@ -758,7 +758,7 @@ transition({UD_RU,UC_RU,UD_RSD,SD_RSD,SC_RSC,UC_RSC}, Local_Eviction, BUSY_BLKD)
ProcessNextState;
}
transition({UD_RSC,SD_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
transition({UD_RU,UD_RSC,SD_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
Initiate_Replacement;
Initiate_Replacement_WB;
Profile_Eviction;