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mem-ruby: sequencer callback for unique writes

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A controller may complete a write without obtaining a full copy of
the line. This patch adds a specific callback for this purpose that
prevents reads to be coalesced with a write on a potentially incomplete
line.

Change-Id: I3775f81699f38e406fee28f92c9c8e06deb3d528
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31269
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bradford Beckmann <bradford.beckmann@gmail.com>
This commit is contained in:
Tiago Mück
2020-06-08 19:01:14 -05:00
parent 1a512d8f77
commit f8e3ba7b7b
3 changed files with 21 additions and 2 deletions
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1
src/mem/ruby/protocol/RubySlicc_Types.sm
View File

@@ -129,6 +129,7 @@ structure (Sequencer, external = "yes") {
void writeCallback(Addr, DataBlock, bool, MachineType);
void writeCallback(Addr, DataBlock, bool, MachineType,
Cycles, Cycles, Cycles);
void writeUniqueCallback(Addr, DataBlock);
// ll/sc support
void writeCallbackScFail(Addr, DataBlock);

12
src/mem/ruby/system/Sequencer.cc
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@@ -352,7 +352,8 @@ Sequencer::writeCallback(Addr address, DataBlock& data,
const bool externalHit, const MachineType mach,
const Cycles initialRequestTime,
const Cycles forwardRequestTime,
const Cycles firstResponseTime)
const Cycles firstResponseTime,
const bool noCoales)
{
//
// Free the whole list as we assume we have had the exclusive access
@@ -370,6 +371,15 @@ Sequencer::writeCallback(Addr address, DataBlock& data,
int aliased_loads = 0;
while (!seq_req_list.empty()) {
SequencerRequest &seq_req = seq_req_list.front();
if (noCoales && !ruby_request) {
// Do not process follow-up requests
// (e.g. if full line no present)
// Reissue to the cache hierarchy
issueRequest(seq_req.pkt, seq_req.m_second_type);
break;
}
if (ruby_request) {
assert(seq_req.m_type != RubyRequestType_LD);
assert(seq_req.m_type != RubyRequestType_Load_Linked);

10
src/mem/ruby/system/Sequencer.hh
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@@ -103,7 +103,15 @@ class Sequencer : public RubyPort
const MachineType mach = MachineType_NUM,
const Cycles initialRequestTime = Cycles(0),
const Cycles forwardRequestTime = Cycles(0),
const Cycles firstResponseTime = Cycles(0));
const Cycles firstResponseTime = Cycles(0),
const bool noCoales = false);
// Write callback that prevents coalescing
void writeUniqueCallback(Addr address, DataBlock& data)
{
writeCallback(address, data, true, MachineType_NUM, Cycles(0),
Cycles(0), Cycles(0), true);
}
void readCallback(Addr address,
DataBlock& data,