Tiago Muck has submitted this change. ( https://gem5-review.googlesource.com/c/public/gem5/+/57389 ) Change subject: mem-ruby: fix CHI wrong response to ReadShared ...................................................................... mem-ruby: fix CHI wrong response to ReadShared 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> --- M src/mem/ruby/protocol/chi/CHI-cache-actions.sm 1 file changed, 38 insertions(+), 22 deletions(-) Approvals: Jason Lowe-Power: Looks good to me, but someone else must approve; Looks good to me, approved Bobby Bruce: Looks good to me, approved kokoro: Regressions pass diff --git a/src/mem/ruby/protocol/chi/CHI-cache-actions.sm b/src/mem/ruby/protocol/chi/CHI-cache-actions.sm index 280ae50..7dbb05c 100644 --- a/src/mem/ruby/protocol/chi/CHI-cache-actions.sm +++ b/src/mem/ruby/protocol/chi/CHI-cache-actions.sm @@ -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 @@ 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 @@ 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"); } -- To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/57389 To unsubscribe, or for help writing mail filters, visit https://gem5-review.googlesource.com/settings Gerrit-Project: public/gem5 Gerrit-Branch: develop Gerrit-Change-Id: Ica7c2afafb55750681b39ae7de99a665689ecb8a Gerrit-Change-Number: 57389 Gerrit-PatchSet: 3 Gerrit-Owner: Tiago Muck <tiago.muck@arm.com> Gerrit-Reviewer: Bobby Bruce <bbruce@ucdavis.edu> Gerrit-Reviewer: Jason Lowe-Power <jason@lowepower.com> Gerrit-Reviewer: Jason Lowe-Power <power.jg@gmail.com> Gerrit-Reviewer: Tiago Muck <tiago.muck@arm.com> Gerrit-Reviewer: kokoro <noreply+kokoro@google.com> Gerrit-MessageType: merged