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mem-ruby: fix CHI wrong response to ReadShared

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When an exclusive cache is responding to a ReadShared and the line is
unique, it send the data in unique state without checking if the line
already has other sharers in other upstream caches.

This patch fixes this issue and also cleans up Send_CompData.

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

Change-Id: Ica7c2afafb55750681b39ae7de99a665689ecb8a
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57389
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
This commit is contained in:
Tiago Mück
2022-03-01 18:48:43 -06:00
committed by Tiago Muck
parent 041cc65899
commit ff5aafa1e9
1 changed files with 15 additions and 22 deletions
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37
src/mem/ruby/protocol/chi/CHI-cache-actions.sm
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2021 ARM Limited
* Copyright (c) 2021-2022 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
@@ -2201,27 +2201,15 @@ action(Send_CompData, desc="") {
bool is_rd_nsd := tbe.reqType == CHIRequestType:ReadNotSharedDirty;
bool is_rd_unique := tbe.reqType == CHIRequestType:ReadUnique;
// if the config allows (or not caching the data) and line has no sharers
bool snd_unique_on_rs := (fwd_unique_on_readshared || tbe.dataToBeInvalid)
&& tbe.dataUnique && tbe.dir_sharers.isEmpty();
// if the request type allows and we won't be caching the data
bool snd_dirty_on_rs := is_rd_shared && !is_rd_nsd && tbe.dataToBeInvalid;
if (is_rd_once) {
tbe.snd_msgType := CHIDataType:CompData_I;
} else if (tbe.dataToBeInvalid) {
// We will drop the data so propagate it's coherent state upstream
if (tbe.dataUnique && tbe.dataDirty) {
tbe.snd_msgType := CHIDataType:CompData_UD_PD;
} else if (tbe.dataUnique) {
tbe.snd_msgType := CHIDataType:CompData_UC;
} else if (tbe.dataDirty) {
if (is_rd_nsd) {
tbe.snd_msgType := CHIDataType:CompData_SC;
} else {
tbe.snd_msgType := CHIDataType:CompData_SD_PD;
}
} else {
tbe.snd_msgType := CHIDataType:CompData_SC;
}
} else if (is_rd_unique ||
(is_rd_shared && tbe.dataUnique &&
fwd_unique_on_readshared && (tbe.dir_ownerExists == false))) {
// propagates dirtyness
} else if (is_rd_unique || (is_rd_shared && snd_unique_on_rs)) {
assert(tbe.dataUnique);
if (tbe.dataDirty) {
tbe.snd_msgType := CHIDataType:CompData_UD_PD;
@@ -2229,8 +2217,13 @@ action(Send_CompData, desc="") {
tbe.snd_msgType := CHIDataType:CompData_UC;
}
} else if (is_rd_shared) {
// still keeping a copy so can send as SC
tbe.snd_msgType := CHIDataType:CompData_SC;
if (tbe.dataDirty && snd_dirty_on_rs) {
tbe.snd_msgType := CHIDataType:CompData_SD_PD;
} else {
// notice the MaintainCoherence will send WriteClean if the line
// is dirty and we won't be caching the data
tbe.snd_msgType := CHIDataType:CompData_SC;
}
} else {
error("Invalid request type");
}