Add highest priority wq to the kernel.

The critical wq allows pushing to remote cores and cores never steal from the critical wq.

Add highest priority wq to the kernel.
e7be4f53 · Silas Boyd-Wickizer · 828175bd · e7be4f53 · e7be4f53 · e7be4f53
--- a/include/wq.hh
+++ b/include/wq.hh
@@ -8,7 +8,6 @@ class work;

 int             wq_trywork(void);
 int             wq_push(work *w);
-int             wq_pushto(work *w, int tcpuid);
 void            wq_dump(void);
 size_t          wq_size(void);
 void            initwq(void);
@@ -48,7 +47,7 @@ class wq {
 public:
  wq();
  int push(work *w, int tcpuid);
-  int trywork();
+  int trywork(bool steal = true);
  void dump();

  static void* operator new(unsigned long);
@@ -84,6 +83,10 @@ private:
 void* xallocwork(unsigned long nbytes);
 void  xfreework(void* ptr, unsigned long nbytes);

+#if defined(XV6_KERNEL)
+int   wqcrit_push(work* w, int c);
+#endif
+
 #if defined(XV6_USER)
 void* wqalloc(unsigned long nbytes);
 void  wqfree(void *ptr);

--- a/kernel/exec.cc
+++ b/kernel/exec.cc
@@ -248,7 +248,7 @@ exec(const char *path, char **argv, void *ascopev)
  w->rip = (void*) exec_cleanup;
  w->arg0 = oldvmap;
  w->arg1 = olduwq;
-  assert(wq_pushto(w, myproc()->exec_cpuid_) >= 0);
+  assert(wqcrit_push(w, myproc()->exec_cpuid_) >= 0);

  gc_end_epoch();
  return 0;

--- a/kernel/kalloc.cc
+++ b/kernel/kalloc.cc
@@ -287,7 +287,7 @@ initkalloc(u64 mbaddr)

    strncpy(slabmem[slab_wq][c].name, " wq", MAXNAME);
    slabmem[slab_wq][c].size = PGROUNDUP(wq_size());
-    slabmem[slab_wq][c].ninit = NCPU;
+    slabmem[slab_wq][c].ninit = 2;

    strncpy(slabmem[slab_userwq][c].name, " uwq", MAXNAME);
    slabmem[slab_userwq][c].size = USERWQSIZE;

--- a/kernel/proc.cc
+++ b/kernel/proc.cc
@@ -443,7 +443,7 @@ wait(void)
          assert(w);
          w->rip = (void*) finishproc;
          w->arg0 = p;
-          assert(wq_pushto(w, p->run_cpuid_) >= 0);
+          assert(wqcrit_push(w, p->run_cpuid_) >= 0);

          if (!xnspid->remove(pid, &p))
            panic("wait: ns_remove");

--- a/kernel/wqkern.cc
+++ b/kernel/wqkern.cc
@@ -7,6 +7,7 @@
 #include "wq.hh"

 static wq *wq_;
+static wq *wqcrit_;

 void*
 xallocwork(unsigned long nbytes)
@@ -33,15 +34,15 @@ wq_push(work *w)
 }

 int
-wq_pushto(work *w, int tcpuid)
+wqcrit_push(work *w, int c)
 {
-  return wq_->push(w, tcpuid);
+  return wqcrit_->push(w, c);
 }

 int
 wq_trywork(void)
 {
-  return wq_->trywork();
+  return wqcrit_->trywork(false) || wq_->trywork(true);
 }

 void
@@ -54,4 +55,7 @@ void
 initwq(void)
 {
  wq_ = new wq();
+  wqcrit_ = new wq();
+  if (wq_ == nullptr || wqcrit_ == nullptr)
+    panic("initwq");
 }
--- a/lib/wqlib.cc
+++ b/lib/wqlib.cc
@@ -7,8 +7,6 @@
 #endif
 #include "wq.hh"

-enum { wq_steal_others = 1 };
-
 //
 // wq
 //
@@ -112,9 +110,6 @@ wq::pop(int c)
 inline work*
 wq::steal(int c)
 {
-  if (!wq_steal_others && (c != mycpuid()))
-    return 0;
-
  struct wqueue *q = &q_[c];
  work *w;
  int i;
@@ -137,7 +132,7 @@ wq::steal(int c)
 }

 int
-wq::trywork(void)
+wq::trywork(bool dosteal)
 {
  work *w;
  u64 i, k;
@@ -151,6 +146,9 @@ wq::trywork(void)
    return 1;
  }

+  if (!dosteal)
+    return 0;
+
  for (i = 0; i < NCPU; i++) {
    u64 j = (i+k) % NCPU;