A block allocator for userspace wq work

dffa3cb3 · Silas Boyd-Wickizer · c409bcd3 · dffa3cb3 · dffa3cb3 · dffa3cb3
--- a/include/wq.hh
+++ b/include/wq.hh
@@ -32,14 +32,16 @@ struct cwork : public work {
 #include <stdlib.h>
 #include <assert.h>
 #include <atomic>
-#define xmalloc(n)     malloc(n)
-#define xfree(p, sz)   free(p)
+#define xallocwork(n)    malloc(n)
+#define xfreework(p, sz) free(p)
 #elif defined(XV6_KERNEL)
-#define xmalloc(n)   kmalloc(n, "xmalloc")
-#define xfree(p, sz) kmfree(p, sz)
+#define xallocwork(n)    kmalloc(n, "xallocwork")
+#define xfreework(p, sz) kmfree(p, sz)
 #else
-#define xmalloc(n)     malloc(n)
-#define xfree(p, sz)   free(p)
+extern void* allocwork(unsigned long nbytes);
+extern void  freework(void *ptr);
+#define xallocwork(n)    allocwork(n)
+#define xfreework(n, sz) freework(n)
 #endif

 #include "wqfor.hh"
--- a/include/wqfor.hh
+++ b/include/wqfor.hh
@@ -28,11 +28,11 @@ struct forwork : public work {

  static void* operator new(unsigned long nbytes) {
    assert(nbytes == sizeof(forwork<IT, BODY>));
-    return xmalloc(sizeof(forwork));
+    return xallocwork(sizeof(forwork));
  }

  static void operator delete(void*p) {
-    xfree(p, sizeof(forwork));
+    xfreework(p, sizeof(forwork));
  }

  IT &it_;

--- a/lib/Makefrag
+++ b/lib/Makefrag
@@ -2,7 +2,7 @@ $(O)/lib/%.o: CFLAGS:=$(CFLAGS) -DXV6_USER
 $(O)/lib/%.o: CXXFLAGS:=$(CXXFLAGS) -DXV6_USER

 ULIB = ulib.o usys.o printf.o umalloc.o uthread.o fmt.o stream.o ipc.o \
-       threads.o crt.o wq.o perf.o
+       threads.o crt.o wq.o perf.o wqalloc.o
 ULIB := $(addprefix $(O)/lib/, $(ULIB))

 .PRECIOUS: $(O)/lib/%.o

--- a/lib/wq.cc
+++ b/lib/wq.cc
@@ -247,7 +247,7 @@ void*
 cwork::operator new(unsigned long nbytes)
 {
  assert(nbytes == sizeof(cwork));
-  return xmalloc(sizeof(cwork));
+  return xallocwork(sizeof(cwork));
 }

 void*
@@ -260,5 +260,5 @@ cwork::operator new(unsigned long nbytes, cwork* buf)
 void
 cwork::operator delete(void *p)
 {
-  xfree(p, sizeof(cwork));
+  xfreework(p, sizeof(cwork));
 }
--- a/lib/wqalloc.cc
+++ b/lib/wqalloc.cc
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "lib.h"
+#include "percpu.hh"
+
+#define WQCHUNKSZ 8192
+#define WQBLOCKSZ 128
+static_assert(WQCHUNKSZ%WQBLOCKSZ == 0, "Bad sizes");
+
+struct wqblock {
+  wqblock* next;
+};
+  
+percpu<wqblock*> block;
+
+static bool
+refill(void)
+{
+  long r = map(0, WQCHUNKSZ);
+  if (r < 0)
+    return false;
+
+  for (uptr p = r; p < r+WQCHUNKSZ; p += WQBLOCKSZ) {
+    wqblock* n = (wqblock*)p;
+    n->next = *block;
+    *block = n;
+  }
+  return true;
+}
+
+void*
+allocwork(unsigned long nbytes)
+{
+  assert(nbytes <= WQBLOCKSZ);
+
+  if (*block == nullptr)
+    if (!refill())
+      return nullptr;
+
+  wqblock *r = *block;
+  *block = r->next;
+  return r;
+}
+
+void
+freework(void *ptr)
+{
+  wqblock* b = (wqblock*) ptr;
+  b->next = *block;
+  *block = b;
+}