From 8db233c9b721abf66a47caf2d79c4e5c97c9a8fd Mon Sep 17 00:00:00 2001 From: Andrew Waterman Date: Mon, 30 Jul 2012 20:12:11 -0700 Subject: [PATCH] further pipeline the LLC --- uncore/llc.scala | 84 +++++++++++++++++++++++++++++++++++------------- 1 file changed, 62 insertions(+), 22 deletions(-) diff --git a/uncore/llc.scala b/uncore/llc.scala index d95aeff7..89fc5e2f 100644 --- a/uncore/llc.scala +++ b/uncore/llc.scala @@ -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)))