More worker clean up

893b2640 · Silas Boyd-Wickizer · 6fb6add0 · 893b2640 · 893b2640 · 893b2640
--- a/include/uwq.hh
+++ b/include/uwq.hh
@@ -6,13 +6,15 @@ struct padded_length {
 };

 #if defined (XV6_KERNEL)
-#define NWORKERS (NCPU-1)
+bool uwq_trywork(void);

+#define NWORKERS (NCPU-1)
 struct uwq;

 struct uwq_worker {
  uwq_worker(uwq*, proc*);
  long wait();
+  void exit();

  uwq* uwq_;
  proc *proc_;
@@ -24,14 +26,13 @@ struct uwq_worker {
 };

 struct uwq : public referenced, public rcu_freed {
+  friend struct uwq_worker;
+
  static uwq* alloc(vmap* vmap, filetable *ftable);
  bool  haswork();
-  bool  trywork();
-  void* buffer();
+  bool  tryworker();

  void  setuentry(uptr uentry);
-  // XXX(sbw) should be part of struct worker
-  void  tryexit(uwq_worker *w);

  virtual void do_gc(void) { delete this; }

@@ -58,6 +59,4 @@ private:

  uwq_worker* worker_[NCPU];
 };
-
-int             uwq_trywork(void);
 #endif
--- a/include/wq.hh
+++ b/include/wq.hh
@@ -9,10 +9,6 @@ size_t          wq_size(void);
 void            initwq(void);
 void            exitwq(void);

-#if defined(XV6_KERNEL)
-int             uwq_trywork(void);
-#endif
-
 struct work {
  virtual void run() = 0;
 };

--- a/kernel/idle.cc
+++ b/kernel/idle.cc
@@ -8,6 +8,7 @@
 #include "sched.hh"
 #include "percpu.hh"
 #include "wq.hh"
+#include "uwq.hh"
 #include "kmtrace.hh"

 struct idle {
@@ -118,9 +119,7 @@ idleloop(void)
          idlem->heir = p;
        }

-        // XXX(sbw) what should be the policy here?
-        worked = uwq_trywork();
-        if (worked == 1)
+        if (uwq_trywork())
          break;

        worked = wq_trywork();

--- a/kernel/uwq.cc
+++ b/kernel/uwq.cc
-//
-// XXX
-//  - workers should have a uwq
-//  - pin workers
-
 #include "types.h"
 #include "amd64.h"
 #include "kernel.hh"
@@ -20,9 +15,11 @@ extern "C" {
 #include "kern_c.h"
 }

-int
+bool
 uwq_trywork(void)
 {
+  // Returning true means uwq added a thread to the run queue
+
  u64 i, k;

  // A "random" victim CPU
@@ -33,23 +30,24 @@ uwq_trywork(void)
    if (j == mycpuid())
      continue;
    struct cpu *c = &cpus[j];
-
+    
+    // The gc_epoch is for p and uwq
    scoped_gc_epoch xgc();
    barrier();
+
    struct proc *p = c->proc;
    if (p == nullptr || p->uwq == nullptr)
      continue;
    uwq* uwq = p->uwq;

    if (uwq->haswork()) {
-      if (uwq->trywork())
-        return 1;
-      // XXX(sbw) start a worker thread..
+      if (uwq->tryworker())
+        return true;
      break;
    }
  }

-  return 0;
+  return false;
 }

 long
@@ -72,14 +70,28 @@ uwq_worker::uwq_worker(uwq* u, proc* p)
  initcondvar(&cv_, "worker_cv");
 }

+void
+uwq_worker::exit(void)
+{
+  if (--uwq_->uref_ == 0)
+    gc_delayed(uwq_);
+  release(&lock_);
+  delete this;
+  ::exit();
+}
+
 long
 uwq_worker::wait(void)
 {
  acquire(&lock_);
-  uwq_->tryexit(this);
+  if (uwq_->ref() == 0)
+    this->exit();
+
  running_ = false;
  cv_sleep(&cv_, &lock_);
-  uwq_->tryexit(this);
+
+  if (uwq_->ref() == 0)
+    this->exit();
  release(&lock_);
  return 0;
 }
@@ -140,18 +152,6 @@ uwq::~uwq(void)
  ftable_->decref();
 }

-void
-uwq::tryexit(uwq_worker *w)
-{
-  if (ref() == 0) {
-    if (--uref_ == 0)
-      gc_delayed(this);
-    release(&w->lock_);
-    delete w;
-    exit();
-  }
-}
-
 bool
 uwq::haswork(void)
 {
@@ -167,8 +167,9 @@ uwq::haswork(void)
 }

 bool
-uwq::trywork(void)
+uwq::tryworker(void)
 {
+  // Try to start a worker thread
  scoped_acquire lock0(&lock_);

  if (ref() == 0)
@@ -249,12 +250,6 @@ uwq::onzero() const
  u->finish();
 }

-void*
-uwq::buffer(void)
-{
-  return (void*)len_;
-}
-
 void
 uwq::setuentry(uptr uentry)
 {