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mem-ruby: fix Evict request for CHI excl. caches

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Assume core C1 with private L1/L2 and a shared exclusive L3.
C1 has a line in SC state, while the state in the L3 is
RUSC (L3 has exclusive accesses and upstream requester has line in SC).

When C1 evicts the line (Evict request), the L3 has to issue a
WriteEvictFull to the home node, however the L3 doesn't have a copy
of the line.

This fix handling Evict requests when the line state is RUSC. When
the last sharer issues an Evict request, the responder may issue
SnpOnce the obtain a copy the line if needed.

JIRA: https://gem5.atlassian.net/browse/GEM5-1195

Change-Id: Ic8f4e10b38d95cd6d84f8d65b87b0c94fcf52eea
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59991
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
This commit is contained in:
Tiago Mück
2022-05-17 13:20:48 -05:00
committed by Tiago Muck
parent 612f242359
commit e4274cabd9
1 changed files with 25 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
src/mem/ruby/protocol/chi/CHI-cache-actions.sm
View File

@@ -897,18 +897,26 @@ action(Finish_CopyBack_Stale, desc="") {
}
action(Initiate_Evict, desc="") {
tbe.actions.push(Event:SendCompIResp);
assert(tbe.dir_sharers.isElement(tbe.requestor));
assert((tbe.dir_ownerExists == false) || (tbe.dir_owner != tbe.requestor));
tbe.dir_sharers.remove(tbe.requestor);
if ((is_HN == false) && (tbe.dir_sharers.count() == 0) &&
if ((is_HN == false) && (tbe.dir_sharers.count() == 1) &&
(tbe.dataValid == false)) {
tbe.actions.push(Event:SendEvict);
// last sharer and we also don't have a copy the line, so we also need to
// send an eviction downstream
if (tbe.dataUnique) {
// we need to send a WriteEvictFull so need the upstream data before
// we ack the evict
tbe.actions.push(Event:SendSnpOnce);
tbe.actions.push(Event:SendCompIResp);
tbe.actions.push(Event:SendWriteBackOrWriteEvict);
tbe.actions.push(Event:WriteBEPipe);
tbe.actions.push(Event:SendWBData);
} else {
tbe.actions.push(Event:SendCompIResp);
tbe.actions.push(Event:SendEvict);
}
} else {
tbe.actions.push(Event:SendCompIResp);
}
tbe.actions.pushNB(Event:TagArrayWrite);
tbe.actions.push(Event:TagArrayWrite);
}
action(Initiate_MaintainCoherence, desc="") {
@@ -2518,6 +2526,13 @@ action(Send_RespSepData, desc="") {
action(Send_CompI, desc="") {
assert(is_valid(tbe));
// Used to ack Evict request
assert(tbe.dir_sharers.isElement(tbe.requestor));
assert((tbe.dir_ownerExists == false) || (tbe.dir_owner != tbe.requestor));
tbe.dir_sharers.remove(tbe.requestor);
enqueue(rspOutPort, CHIResponseMsg, response_latency) {
out_msg.addr := address;
out_msg.type := CHIResponseType:Comp_I;