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| author | Andreas Hansson <andreas.hansson@arm.com> | 2015-09-25 07:13:54 -0400 |
|---|---|---|
| committer | Andreas Hansson <andreas.hansson@arm.com> | 2015-09-25 07:13:54 -0400 |
| commit | 462c288a757bc4fd50324ebe2f1fd697d53838ab (patch) | |
| tree | 02cc70a4d0682136b458ee59d5c9dad0dfdec00a /src/mem/packet.hh | |
| parent | 3bd78a141ec60ae65d910286c3d99ae7030ba703 (diff) | |
| download | gem5-462c288a757bc4fd50324ebe2f1fd697d53838ab.tar.xz | |
mem: Make the coherent crossbar account for timing snoops
This patch introduces the concept of a snoop latency. Given the
requirement to snoop and forward packets in zero time (due to the
coherency mechanism), the latency is accounted for later.
On a snoop, we establish the latency, and later add it to the header
delay of the packet. To allow multiple caches to contribute to the
snoop latency, we use a separate variable in the packet, and then take
the maximum before adding it to the header delay.
Diffstat (limited to 'src/mem/packet.hh')
| -rw-r--r-- | src/mem/packet.hh | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/mem/packet.hh b/src/mem/packet.hh index 2b667d26d..f33ee120d 100644 --- a/src/mem/packet.hh +++ b/src/mem/packet.hh @@ -324,6 +324,14 @@ class Packet : public Printable uint32_t headerDelay; /** + * Keep track of the extra delay incurred by snooping upwards + * before sending a request down the memory system. This is used + * by the coherent crossbar to account for the additional request + * delay. + */ + uint32_t snoopDelay; + + /** * The extra pipelining delay from seeing the packet until the end of * payload is transmitted by the component that provided it (if * any). This includes the header delay. Similar to the header @@ -582,7 +590,7 @@ class Packet : public Printable */ Packet(const RequestPtr _req, MemCmd _cmd) : cmd(_cmd), req(_req), data(nullptr), addr(0), _isSecure(false), - size(0), headerDelay(0), payloadDelay(0), + size(0), headerDelay(0), snoopDelay(0), payloadDelay(0), senderState(NULL) { if (req->hasPaddr()) { @@ -603,7 +611,7 @@ class Packet : public Printable */ Packet(const RequestPtr _req, MemCmd _cmd, int _blkSize) : cmd(_cmd), req(_req), data(nullptr), addr(0), _isSecure(false), - headerDelay(0), payloadDelay(0), + headerDelay(0), snoopDelay(0), payloadDelay(0), senderState(NULL) { if (req->hasPaddr()) { @@ -628,6 +636,7 @@ class Packet : public Printable addr(pkt->addr), _isSecure(pkt->_isSecure), size(pkt->size), bytesValid(pkt->bytesValid), headerDelay(pkt->headerDelay), + snoopDelay(0), payloadDelay(pkt->payloadDelay), senderState(pkt->senderState) { |