diff options
Diffstat (limited to 'src/runtime/runtime2.go')
| -rw-r--r-- | src/runtime/runtime2.go | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index e652f5be64..ac10ec99fa 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -169,9 +169,13 @@ func efaceOf(ep *interface{}) *eface { // a word that is completely ignored by the GC than to have one for which // only a few updates are ignored. // -// Gs, Ms, and Ps are always reachable via true pointers in the -// allgs, allm, and allp lists or (during allocation before they reach those lists) +// Gs and Ps are always reachable via true pointers in the +// allgs and allp lists or (during allocation before they reach those lists) // from stack variables. +// +// Ms are always reachable via true pointers either from allm or +// freem. Unlike Gs and Ps we do free Ms, so it's important that +// nothing ever hold an muintptr across a safe point. // A guintptr holds a goroutine pointer, but typed as a uintptr // to bypass write barriers. It is used in the Gobuf goroutine state @@ -221,6 +225,15 @@ func (pp puintptr) ptr() *p { return (*p)(unsafe.Pointer(pp)) } //go:nosplit func (pp *puintptr) set(p *p) { *pp = puintptr(unsafe.Pointer(p)) } +// muintptr is a *m that is not tracked by the garbage collector. +// +// Because we do free Ms, there are some additional constrains on +// muintptrs: +// +// 1. Never hold an muintptr locally across a safe point. +// +// 2. Any muintptr in the heap must be owned by the M itself so it can +// ensure it is not in use when the last true *m is released. type muintptr uintptr //go:nosplit @@ -413,7 +426,8 @@ type m struct { inwb bool // m is executing a write barrier newSigstack bool // minit on C thread called sigaltstack printlock int8 - incgo bool // m is executing a cgo call + incgo bool // m is executing a cgo call + freeWait uint32 // if == 0, safe to free g0 and delete m (atomic) fastrand [2]uint32 needextram bool traceback uint8 @@ -440,6 +454,7 @@ type m struct { startingtrace bool syscalltick uint32 thread uintptr // thread handle + freelink *m // on sched.freem // these are here because they are too large to be on the stack // of low-level NOSPLIT functions. @@ -528,12 +543,16 @@ type schedt struct { lock mutex + // When increasing nmidle, nmidlelocked, nmsys, or nmfreed, be + // sure to call checkdead(). + midle muintptr // idle m's waiting for work nmidle int32 // number of idle m's waiting for work nmidlelocked int32 // number of locked m's waiting for work mnext int64 // number of m's that have been created and next M ID maxmcount int32 // maximum number of m's allowed (or die) nmsys int32 // number of system m's not counted for deadlock + nmfreed int64 // cumulative number of freed m's ngsys uint32 // number of system goroutines; updated atomically @@ -560,6 +579,10 @@ type schedt struct { deferlock mutex deferpool [5]*_defer + // freem is the list of m's waiting to be freed when their + // m.exited is set. Linked through m.freelink. + freem *m + gcwaiting uint32 // gc is waiting to run stopwait int32 stopnote note |