[gem5-dev] Change in gem5/gem5[develop]: mem-ruby: MESI_Three_Level LL/SC improvements
Pouya Fotouhi has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/28328 )
Change subject: mem-ruby: MESI_Three_Level LL/SC improvements
..
mem-ruby: MESI_Three_Level LL/SC improvements
This patch fixes the MESI_Three_Level protocols so that it correctly
informers the Ruby sequencer when a line eviction occurs. Furthermore,
the patch allows the protocol to recognize the 'Store_Conditional'
RubyRequestType and shortcuts this operation if the monitored line
has been cleared from the address monitor. This prevents certain
livelock behaviour in which a line could ping-pong between competing
cores.
The patch establishes a new C/C++ preprocessor definition which allows
the Sequencer to send the 'Store_Conditional' RubyRequestType to
MESI_Three_Level instead of 'ST'. This is a temporary measure until
the other protocols explicitely recognize 'Store_Conditional'.
Change-Id: I27ae041ab0e015a4f54f20df666f9c4873c7583d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28328
Reviewed-by: Daniel Carvalho
Maintainer: Bobby R. Bruce
Tested-by: kokoro
---
M src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
M src/mem/ruby/system/SConscript
M src/mem/ruby/system/Sequencer.cc
3 files changed, 77 insertions(+), 23 deletions(-)
Approvals:
Daniel Carvalho: Looks good to me, approved
Bobby R. Bruce: Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
b/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
index b74a727..14fb07a 100644
--- a/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
+++ b/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
@@ -121,6 +121,8 @@
Ack,desc="Ack for processor";
WB_Ack,desc="Ack for replacement";
+
+Failed_SC,desc="Store conditional request that will fail";
}
// TYPES
@@ -257,7 +259,8 @@
return Event:Load;
} else if (type == RubyRequestType:IFETCH) {
return Event:Ifetch;
-} else if ((type == RubyRequestType:ST) || (type ==
RubyRequestType:ATOMIC)) {
+} else if ((type == RubyRequestType:ST) || (type ==
RubyRequestType:ATOMIC)
+ || (type == RubyRequestType:Store_Conditional)) {
return Event:Store;
} else {
error("Invalid RubyRequestType");
@@ -349,36 +352,51 @@
}
}
} else {
-
// *** DATA ACCESS ***
Entry Dcache_entry := getDCacheEntry(in_msg.LineAddress);
+
+ // early out for failed store conditionals
+
+ if (in_msg.Type == RubyRequestType:Store_Conditional) {
+ if (!sequencer.llscCheckMonitor(in_msg.LineAddress)) {
+trigger(Event:Failed_SC, in_msg.LineAddress,
+Dcache_entry, TBEs[in_msg.LineAddress]);
+}
+ }
+
if (is_valid(Dcache_entry)) {
// The tag matches for the L0, so the L0 ask the L1 for it
trigger(mandatory_request_type_to_event(in_msg.Type),
in_msg.LineAddress,
Dcache_entry, TBEs[in_msg.LineAddress]);
} else {
-
-// Check to see if it is in the OTHER L0
-Entry Icache_entry := getICacheEntry(in_msg.LineAddress);
-if (is_valid(Icache_entry)) {
- // The block is in the wrong L0, put the request on the
queue to the private L1
- trigger(Event:L0_Replacement, in_msg.LineAddress,
- Icache_entry, TBEs[in_msg.LineAddress]);
-}
-
-if (Dcache.cacheAvail(in_msg.LineAddress)) {
- // L1 does't have the line, but we have space for it
- // in the L0 let's see if the L1 has it
- trigger(mandatory_request_type_to_event(in_msg.Type),
in_msg.LineAddress,
- Dcache_entry, TBEs[in_msg.LineAddress]);
+// if the request is not valid, the store conditional will fail
+if (in_msg.Type == RubyRequestType:Store_Conditional) {
+// if the line is not valid, it can't be locked
+trigger(Event:Failed_SC, in_msg.LineAddress,
+Dcache_entry, TBEs[in_msg.LineAddress]);
} else {
- // No room in the L1, so we need to make room in the L0
- // Check if the line we want to evict is not locked
- Addr addr := Dcache.cacheProbe(in_msg.LineAddress);
- check_on_cache_probe(mandatoryQueue_in, addr);
- trigger(Event:L0_Replacement, addr,
- getDCacheEntry(addr),
- TBEs[addr]);
+ // Check to see if it is in the OTHER L0
+ Entry Icache_entry := getICacheEntry(in_msg.LineAddress);
+ if (is_valid(Icache_entry)) {
+// The block is in the wrong L0, put the request on the
queue to the private L1
+
[gem5-dev] Change in gem5/gem5[develop]: mem-ruby: MESI_Three_Level LL/SC improvements
Hello Timothy Hayes,
I'd like you to do a code review. Please visit
https://gem5-review.googlesource.com/c/public/gem5/+/28328
to review the following change.
Change subject: mem-ruby: MESI_Three_Level LL/SC improvements
..
mem-ruby: MESI_Three_Level LL/SC improvements
This patch fixes the MESI_Three_Level protocols so that it correctly
informers the Ruby sequencer when a line eviction occurs. Furthermore,
the patch allows the protocol to recognize the 'Store_Conditional'
RubyRequestType and shortcuts this operation if the monitored line
has been cleared from the address monitor. This prevents certain
livelock behaviour in which a line could ping-pong between competing
cores.
The patch establishes a new C/C++ preprocessor definition which allows
the Sequencer to send the 'Store_Conditional' RubyRequestType to
MESI_Three_Level instead of 'ST'. This is a temporary measure until
the other protocols explicitely recognize 'Store_Conditional'.
Change-Id: I27ae041ab0e015a4f54f20df666f9c4873c7583d
---
M src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
M src/mem/ruby/system/SConscript
M src/mem/ruby/system/Sequencer.cc
3 files changed, 77 insertions(+), 23 deletions(-)
diff --git a/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
b/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
index b74a727..14fb07a 100644
--- a/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
+++ b/src/mem/ruby/protocol/MESI_Three_Level-L0cache.sm
@@ -121,6 +121,8 @@
Ack,desc="Ack for processor";
WB_Ack,desc="Ack for replacement";
+
+Failed_SC,desc="Store conditional request that will fail";
}
// TYPES
@@ -257,7 +259,8 @@
return Event:Load;
} else if (type == RubyRequestType:IFETCH) {
return Event:Ifetch;
-} else if ((type == RubyRequestType:ST) || (type ==
RubyRequestType:ATOMIC)) {
+} else if ((type == RubyRequestType:ST) || (type ==
RubyRequestType:ATOMIC)
+ || (type == RubyRequestType:Store_Conditional)) {
return Event:Store;
} else {
error("Invalid RubyRequestType");
@@ -349,36 +352,51 @@
}
}
} else {
-
// *** DATA ACCESS ***
Entry Dcache_entry := getDCacheEntry(in_msg.LineAddress);
+
+ // early out for failed store conditionals
+
+ if (in_msg.Type == RubyRequestType:Store_Conditional) {
+ if (!sequencer.llscCheckMonitor(in_msg.LineAddress)) {
+trigger(Event:Failed_SC, in_msg.LineAddress,
+Dcache_entry, TBEs[in_msg.LineAddress]);
+}
+ }
+
if (is_valid(Dcache_entry)) {
// The tag matches for the L0, so the L0 ask the L1 for it
trigger(mandatory_request_type_to_event(in_msg.Type),
in_msg.LineAddress,
Dcache_entry, TBEs[in_msg.LineAddress]);
} else {
-
-// Check to see if it is in the OTHER L0
-Entry Icache_entry := getICacheEntry(in_msg.LineAddress);
-if (is_valid(Icache_entry)) {
- // The block is in the wrong L0, put the request on the
queue to the private L1
- trigger(Event:L0_Replacement, in_msg.LineAddress,
- Icache_entry, TBEs[in_msg.LineAddress]);
-}
-
-if (Dcache.cacheAvail(in_msg.LineAddress)) {
- // L1 does't have the line, but we have space for it
- // in the L0 let's see if the L1 has it
- trigger(mandatory_request_type_to_event(in_msg.Type),
in_msg.LineAddress,
- Dcache_entry, TBEs[in_msg.LineAddress]);
+// if the request is not valid, the store conditional will fail
+if (in_msg.Type == RubyRequestType:Store_Conditional) {
+// if the line is not valid, it can't be locked
+trigger(Event:Failed_SC, in_msg.LineAddress,
+Dcache_entry, TBEs[in_msg.LineAddress]);
} else {
- // No room in the L1, so we need to make room in the L0
- // Check if the line we want to evict is not locked
- Addr addr := Dcache.cacheProbe(in_msg.LineAddress);
- check_on_cache_probe(mandatoryQueue_in, addr);
- trigger(Event:L0_Replacement, addr,
- getDCacheEntry(addr),
- TBEs[addr]);
+ // Check to see if it is in the OTHER L0
+ Entry Icache_entry := getICacheEntry(in_msg.LineAddress);
+ if (is_valid(Icache_entry)) {
+// The block is in the wrong L0, put the request on the
queue to the private L1
+trigger(Event:L0_Replacement, in_msg.LineAddress,
+Icache_entry, TBEs[in_msg.LineAddress]);
+ }
+
+ if (Dcache.cacheAvail(in_msg.LineAddress)) {
+//
