wq tweak: __wq_run now inherits the frame of the thread it's running.

8a620c2e · Silas Boyd-Wickizer · e6668071 · 8a620c2e · 8a620c2e · 8a620c2e
--- a/cpu.h
+++ b/cpu.h
 #include "mmu.h"

+struct wqframe;
+
 // Per-CPU state
 struct cpu {
-
  u8 id;                       // Local APIC ID; index into cpus[] below
  int ncli;                    // Depth of pushcli nesting.
  int intena;                  // Were interrupts enabled before pushcli?
@@ -10,6 +11,7 @@ struct cpu {
  struct taskstate ts;         // Used by x86 to find stack for interrupt
  struct context *scheduler;   // swtch() here to enter scheduler
  u64 last_rcu_gc_ticks;
+  struct wqframe *wqframe;

  // Cpu-local storage variables; see below
  struct cpu *cpu;

--- a/param.h
+++ b/param.h
@@ -18,4 +18,4 @@
 #define CPUKSTACKS   (NPROC + NCPU)
 #define QUANTUN      10  // scheduling time quantum and tick length (in msec)
 #define WQSHIFT      4   // 2^WORKSHIFT work queue slots
-#define WQENABLE     0   // Enable work queue
+#define WQENABLE     1   // Enable work queue
--- a/wq.c
+++ b/wq.c
@@ -51,7 +51,7 @@ struct wqthread {
  u64 rip;
  u64 arg0;
  u64 arg1;
-  volatile u64 *ref;  // pointer to parent wqframe.ref
+  struct wqframe *frame;  // parent wqframe
  __padout__;
 } __mpalign__;

@@ -75,7 +75,7 @@ wq_cur(void)
 static struct wqframe *
 wq_frame(void)
 {
-  return &myproc()->wqframe;
+  return mycpu()->wqframe;
 }

 static struct wqstat *
@@ -144,8 +144,12 @@ static void
 __wq_run(struct wqthread *th)
 {
  void (*fn)(uptr arg0, uptr arg1) = (void*)th->rip;
+  struct wqframe *old = mycpu()->wqframe;
+
+  mycpu()->wqframe = th->frame;
  fn(th->arg0, th->arg1);
-  subfetch(th->ref, 1);
+  mycpu()->wqframe = old;
+  subfetch(&th->frame->ref, 1);
  kfree(th);
 }

@@ -166,7 +170,7 @@ wq_push(void *rip, u64 arg0, u64 arg1)
  th->rip = (uptr) rip;
  th->arg0 = arg0;
  th->arg1 = arg1;
-  th->ref = &wq_frame()->ref;
+  th->frame = wq_frame();

  if (__wq_push(wq_cur(), th)) {
    kfree(th);
@@ -216,6 +220,7 @@ wq_start(void)
  pushcli();
  if (myproc()->wqframe.ref != 0)
    panic("wq_start");
+  mycpu()->wqframe = &myproc()->wqframe;
 }

 // End of the current work queue frame.
@@ -224,7 +229,7 @@ wq_start(void)
 void
 wq_end(void)
 {
-  while (myproc()->wqframe.ref != 0) {
+  while (wq_frame()->ref != 0) {
    struct wqthread *th;
    int i;

@@ -239,6 +244,7 @@ wq_end(void)
      }
    }
  }
+  mycpu()->wqframe = NULL;
  popcli();
 }