runtime: update a few comments

noescape is now 0 instructions with the SSA backend.
fast atomics are no longer a TODO (at least for amd64).

Change-Id: Ib6e06f7471bef282a47ba236d8ce95404bb60a42
Reviewed-on: https://go-review.googlesource.com/28087
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index e693f7e05f868a715e95094c8709f9d7d4e9a91a..75e09b3ab7c10ff7d416d1453489c63df16354c6 100644 (file)
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -543,7 +543,7 @@ func ready(gp *g, traceskip int, next bool) {
        // status is Gwaiting or Gscanwaiting, make Grunnable and put on runq
        casgstatus(gp, _Gwaiting, _Grunnable)
        runqput(_g_.m.p.ptr(), gp, next)
-       if atomic.Load(&sched.npidle) != 0 && atomic.Load(&sched.nmspinning) == 0 { // TODO: fast atomic
+       if atomic.Load(&sched.npidle) != 0 && atomic.Load(&sched.nmspinning) == 0 {
                wakep()
        }
        _g_.m.locks--
@@ -1901,7 +1901,7 @@ top:
        // If number of spinning M's >= number of busy P's, block.
        // This is necessary to prevent excessive CPU consumption
        // when GOMAXPROCS>>1 but the program parallelism is low.
-       if !_g_.m.spinning && 2*atomic.Load(&sched.nmspinning) >= procs-atomic.Load(&sched.npidle) { // TODO: fast atomic
+       if !_g_.m.spinning && 2*atomic.Load(&sched.nmspinning) >= procs-atomic.Load(&sched.npidle) {
                goto stop
        }
        if !_g_.m.spinning {
@@ -2341,7 +2341,7 @@ func reentersyscall(pc, sp uintptr) {
                save(pc, sp)
        }
 
-       if atomic.Load(&sched.sysmonwait) != 0 { // TODO: fast atomic
+       if atomic.Load(&sched.sysmonwait) != 0 {
                systemstack(entersyscall_sysmon)
                save(pc, sp)
        }
@@ -2806,7 +2806,7 @@ func newproc1(fn *funcval, argp *uint8, narg int32, nret int32, callerpc uintptr
        }
        runqput(_p_, newg, true)
 
-       if atomic.Load(&sched.npidle) != 0 && atomic.Load(&sched.nmspinning) == 0 && unsafe.Pointer(fn.fn) != unsafe.Pointer(funcPC(main)) { // TODO: fast atomic
+       if atomic.Load(&sched.npidle) != 0 && atomic.Load(&sched.nmspinning) == 0 && unsafe.Pointer(fn.fn) != unsafe.Pointer(funcPC(main)) {
                wakep()
        }
        _g_.m.locks--
@@ -3604,7 +3604,7 @@ func sysmon() {
                        delay = 10 * 1000
                }
                usleep(delay)
-               if debug.schedtrace <= 0 && (sched.gcwaiting != 0 || atomic.Load(&sched.npidle) == uint32(gomaxprocs)) { // TODO: fast atomic
+               if debug.schedtrace <= 0 && (sched.gcwaiting != 0 || atomic.Load(&sched.npidle) == uint32(gomaxprocs)) {
                        lock(&sched.lock)
                        if atomic.Load(&sched.gcwaiting) != 0 || atomic.Load(&sched.npidle) == uint32(gomaxprocs) {
                                atomic.Store(&sched.sysmonwait, 1)

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 72951ae0b267b974dd0a9d4ec59bd70d057186c4..0f75663b9a7e3ca0e903793a30919756a770a08b 100644 (file)
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -90,7 +90,7 @@ func memequal(a, b unsafe.Pointer, size uintptr) bool
 // noescape hides a pointer from escape analysis.  noescape is
 // the identity function but escape analysis doesn't think the
 // output depends on the input.  noescape is inlined and currently
-// compiles down to a single xor instruction.
+// compiles down to zero instructions.
 // USE CAREFULLY!
 //go:nosplit
 func noescape(p unsafe.Pointer) unsafe.Pointer {