riscv/rocket-chip
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further pipeline the LLC

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This commit is contained in:
Andrew Waterman 2012-07-30 20:12:11 -07:00
parent 914b6b622d
commit 85dc34df80
1 changed files with 62 additions and 22 deletions
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84
uncore/llc.scala
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@ -14,7 +14,6 @@ class BigMem[T <: Data](n: Int, readLatency: Int, leaf: Mem[Bits])(gen: => T) ex
val wmask = gen.asInput
val rdata = gen.asOutput
}
require(readLatency >= 0 && readLatency <= 2)
val data = gen
val colMux = if (2*data.width <= leaf.data.width && n > leaf.n) 1 << math.floor(math.log(leaf.data.width/data.width)/math.log(2)).toInt else 1
val nWide = if (data.width > leaf.data.width) 1+(data.width-1)/leaf.data.width else 1
@ -28,9 +27,6 @@ class BigMem[T <: Data](n: Int, readLatency: Int, leaf: Mem[Bits])(gen: => T) ex
val cond = Vec(nDeep) { Bool() }
val ren = Vec(nDeep) { Bool() }
val reg_ren = Vec(nDeep) { Reg() { Bool() } }
val reg2_ren = Vec(nDeep) { Reg() { Bool() } }
val reg_raddr = Vec(nDeep) { Reg() { UFix() } }
val reg2_raddr = Vec(nDeep) { Reg() { UFix() } }
val renOut = Vec(nDeep) { Bool() }
val raddrOut = Vec(nDeep) { UFix() }
val rdata = Vec(nDeep) { Vec(nWide) { Bits() } }
@ -40,11 +36,14 @@ class BigMem[T <: Data](n: Int, readLatency: Int, leaf: Mem[Bits])(gen: => T) ex
cond(i) := (if (nDeep == 1) io.en else io.en && UFix(i) === io.addr(log2Up(n)-1, log2Up(n/nDeep)))
ren(i) := cond(i) && !io.rw
reg_ren(i) := ren(i)
reg2_ren(i) := reg_ren(i)
when (ren(i)) { reg_raddr(i) := io.addr }
when (reg_ren(i)) { reg2_raddr(i) := reg_raddr(i) }
renOut(i) := (if (readLatency > 1) reg2_ren(i) else if (readLatency > 0) reg_ren(i) else ren(i))
raddrOut(i) := (if (readLatency > 1) reg2_raddr(i) else if (readLatency > 0) reg_raddr(i) else io.addr)
renOut(i) := ren(i)
raddrOut(i) := io.addr
if (readLatency > 0) {
val r = Pipe(ren(i), io.addr, readLatency)
renOut(i) := r.valid
raddrOut(i) := r.bits
}
for (j <- 0 until nWide) {
val mem = leaf.clone
@ -64,11 +63,8 @@ class BigMem[T <: Data](n: Int, readLatency: Int, leaf: Mem[Bits])(gen: => T) ex
dout = mem(idx)
} else if (readLatency == 1) {
dout = dout1
} else {
val dout2 = Reg() { Bits() }
when (reg_ren(i)) { dout2 := dout1 }
dout = dout2
}
} else
dout = Pipe(reg_ren(i), dout1, readLatency-1).bits
rdata(i)(j) := dout
}
@ -238,7 +234,7 @@ class LLCWriteback(requestors: Int) extends Component
io.mem.req_data.bits := io.data(who).bits
}
class LLCData(sets: Int, ways: Int, leaf: Mem[Bits]) extends Component
class LLCData(latency: Int, sets: Int, ways: Int, leaf: Mem[Bits]) extends Component
{
val io = new Bundle {
val req = (new FIFOIO) { new LLCDataReq(ways) }.flip
@ -251,13 +247,13 @@ class LLCData(sets: Int, ways: Int, leaf: Mem[Bits]) extends Component
val mem_resp_way = UFix(INPUT, log2Up(ways))
}
val data = new BigMem(sets*ways*REFILL_CYCLES, 2, leaf)(Bits(width = MEM_DATA_BITS))
val data = new BigMem(sets*ways*REFILL_CYCLES, latency, leaf)(Bits(width = MEM_DATA_BITS))
class QEntry extends MemResp {
val isWriteback = Bool()
override def clone = new QEntry().asInstanceOf[this.type]
}
val q = (new queue(4)) { new QEntry }
val qReady = q.io.count <= UFix(q.entries - 3)
val q = (new queue(latency+2)) { new QEntry }
val qReady = q.io.count <= UFix(q.entries-latency-1)
val valid = Reg(resetVal = Bool(false))
val req = Reg() { io.req.bits.clone }
val count = Reg(resetVal = UFix(0, log2Up(REFILL_CYCLES)))
@ -287,10 +283,11 @@ class LLCData(sets: Int, ways: Int, leaf: Mem[Bits]) extends Component
data.io.wdata := io.mem_resp.bits.data
}
q.io.enq.valid := Reg(Reg(data.io.en && !data.io.rw, resetVal = Bool(false)), resetVal = Bool(false))
q.io.enq.bits.tag := Reg(Reg(Mux(valid, req.tag, io.req.bits.tag)))
val tagPipe = Pipe(data.io.en && !data.io.rw, Mux(valid, req.tag, io.req.bits.tag), latency)
q.io.enq.valid := tagPipe.valid
q.io.enq.bits.tag := tagPipe.bits
q.io.enq.bits.isWriteback := Pipe(Mux(valid, req.isWriteback, io.req.bits.isWriteback), Bool(false), latency).valid
q.io.enq.bits.data := data.io.rdata
q.io.enq.bits.isWriteback := Reg(Reg(Mux(valid, req.isWriteback, io.req.bits.isWriteback)))
io.req.ready := !valid && Mux(io.req.bits.isWriteback, io.writeback.ready, Bool(true))
io.req_data.ready := !io.mem_resp.valid && Mux(valid, req.rw, io.req.valid && io.req.bits.rw)
@ -305,6 +302,49 @@ class LLCData(sets: Int, ways: Int, leaf: Mem[Bits]) extends Component
io.writeback_data.bits := q.io.deq.bits
}
class MemReqArb(n: Int) extends Component // UNTESTED
{
val io = new Bundle {
val cpu = Vec(n) { new ioMem().flip }
val mem = new ioMem
}
val lock = Reg(resetVal = Bool(false))
val locker = Reg() { UFix() }
val arb = new RRArbiter(n)(new MemReqCmd)
val respWho = io.mem.resp.bits.tag(log2Up(n)-1,0)
val respTag = io.mem.resp.bits.tag >> UFix(log2Up(n))
for (i <- 0 until n) {
val me = UFix(i, log2Up(n))
arb.io.in(i).valid := io.cpu(i).req_cmd.valid
arb.io.in(i).bits := io.cpu(i).req_cmd.bits
arb.io.in(i).bits.tag := Cat(io.cpu(i).req_cmd.bits.tag, me)
io.cpu(i).req_cmd.ready := arb.io.in(i).ready
io.cpu(i).req_data.ready := Bool(false)
val getLock = io.cpu(i).req_cmd.fire() && io.cpu(i).req_cmd.bits.rw && !lock
val haveLock = lock && locker === me
when (getLock) {
lock := Bool(true)
locker := UFix(i)
}
when (getLock || haveLock) {
io.cpu(i).req_data.ready := io.mem.req_data.ready
io.mem.req_data.valid := Bool(true)
io.mem.req_data.bits := io.cpu(i).req_data.bits
}
io.cpu(i).resp.valid := io.mem.resp.valid && respWho === me
io.cpu(i).resp.bits := io.mem.resp.bits
io.cpu(i).resp.bits.tag := respTag
}
io.mem.resp.ready := io.cpu(respWho).resp.ready
val unlock = Counter(io.mem.req_data.fire(), REFILL_CYCLES)._2
when (unlock) { lock := Bool(false) }
}
class DRAMSideLLC(sets: Int, ways: Int, outstanding: Int, tagLeaf: Mem[Bits], dataLeaf: Mem[Bits]) extends Component
{
val io = new Bundle {
@ -319,7 +359,7 @@ class DRAMSideLLC(sets: Int, ways: Int, outstanding: Int, tagLeaf: Mem[Bits], da
val dataArb = (new Arbiter(2)) { new LLCDataReq(ways) }
val mshr = new LLCMSHRFile(sets, ways, outstanding)
val tags = new BigMem(sets, 1, tagLeaf)(Bits(width = metaWidth*ways))
val data = new LLCData(sets, ways, dataLeaf)
val data = new LLCData(3, sets, ways, dataLeaf)
val writeback = new LLCWriteback(2)
val initCount = Reg(resetVal = UFix(0, log2Up(sets+1)))