A bunch of random kernlet/pread hacking

44772003 · Silas Boyd-Wickizer · 39024ea6 · 44772003 · 44772003 · 44772003
--- a/ipc.hh
+++ b/ipc.hh
-struct ipcctl {
+#define IPC_NMSG 16
+typedef u32 msgid_t;
+#define NULL_MSGID (-1)
+
+#define IPC_NPAGE ((KSHAREDSIZE/PGSIZE) - 1)
+typedef u32 pageid_t;
+#define NULL_PAGEID (-1)
+
+struct ipcmsg {
  volatile char done:1;
  volatile char submitted:1;

+  pageid_t pageid;
  off_t off;
  volatile long result;
 };
+
+struct ipcctl {
+  int msghead;
+  int msgtail;
+  struct ipcmsg msg[IPC_NMSG];
+
+  int pagehead;
+  int pagetail;
+};
--- a/kern_c.h
+++ b/kern_c.h
 #include "mmu.h"
 #include "lib.h"

+struct ipcmsg;
+
 // console.c
 void            consoleintr(int(*)(void));

@@ -44,7 +46,7 @@ long sys_bind(int, void*, int);
 long sys_listen(int, int);
 long sys_accept(int, void*, void*);
 long sys_pread(int fd, void *ubuf, size_t count, off_t offset);
-long sys_kernlet(int, size_t, off_t);
+long sys_kernlet(int, size_t, off_t, u32, u32);
 extern long (*syscalls[])(u64, u64, u64, u64, u64, u64);

 // other exported/imported functions

--- a/kernel.hh
+++ b/kernel.hh
@@ -335,7 +335,7 @@ long sys_bind(int, void*, int);
 long sys_listen(int, int);
 long sys_accept(int, void*, void*);
 long sys_pread(int fd, void *ubuf, size_t count, off_t offset);
-long sys_kernlet(int, size_t, off_t);
+long sys_kernlet(int, size_t, off_t, u32, u32);
 extern long (*syscalls[])(u64, u64, u64, u64, u64, u64);

 // other exported/imported functions

--- a/kernlet.cc
+++ b/kernlet.cc
@@ -10,56 +10,67 @@
 #include "vm.hh"
 #include "file.hh"

+static_assert(sizeof(struct ipcctl) < PGSIZE, "struct ipcctl too large");
+
 static void
-pread_work(struct work *w, void *a0, void *a1, void *a2, void *a3)
+pread_work(struct work *w, void *a0, void *a1, void *a2,
+           void *a3, void *a4)
 {
  struct inode *ip = (inode*) a0;
-  void *kshared = (void*) a1;
-  struct ipcctl *ipc = (ipcctl*) kshared;
-  size_t count = (uptr)a2;
-  off_t off = (uptr)a3;
+  size_t count = (uptr)a1;
+  off_t off = (uptr)a2;
+  struct ipcmsg *msg = (struct ipcmsg*) a3;
+  void *ubuf = (void*) a4;
  int r;

-  if (count > KSHAREDSIZE-PGSIZE)
-    panic("pread_work");
-
-  //cprintf("1: %p %p %lu %lu\n", ip, buf, count, off);
-
  ilock(ip, 0);
-  r = readi(ip, ((char*)kshared)+PGSIZE, off, count);
+  r = readi(ip, (char*)ubuf, off, count);
  iunlock(ip);
  
-  ipc->result = r;
+  msg->result = r;
  barrier();
-  ipc->done = 1;
+  msg->done = 1;

  iput(ip);
 }

 static struct work *
-pread_allocwork(struct inode *ip, void *buf, size_t count, off_t off)
+pread_allocwork(struct inode *ip, size_t count, off_t off,
+                struct ipcmsg *msg, void *ubuf)
 {
  struct work *w = allocwork();
  if (w == NULL)
    return 0;

-  //cprintf("0: %p %p %lu %lu\n", ip, buf, count, off);
-
  w->rip = (void*) pread_work;
  w->arg0 = ip;
-  w->arg1 = buf;
-  w->arg2 = (void*)count;
-  w->arg3 = (void*)off;
-  
+  w->arg1 = (void*)count;
+  w->arg2 = (void*)off;
+  w->arg3 = msg;
+  w->arg4 = ubuf;
+
  return w;
 }

 long
-sys_kernlet(int fd, size_t count, off_t off)
+sys_kernlet(int fd, size_t count, off_t off,
+            msgid_t msgid, pageid_t pageid)
 {
  struct file *f;
  struct work *w;
-  struct ipcctl *ipc = (struct ipcctl *)myproc()->vmap->kshared;
+
+  char *kshared = myproc()->vmap->kshared;
+  struct ipcctl *ipcctl = (struct ipcctl*)kshared;
+  struct ipcmsg *msg;
+  void *ubuf;
+
+  if (msgid > IPC_NMSG)
+    return -1;
+  if (pageid > IPC_NPAGE)
+    return -1;
+  
+  msg = &ipcctl->msg[msgid];
+  ubuf = (kshared+PGSIZE+(pageid*PGSIZE));

  if(fd < 0 || fd >= NOFILE || (f=myproc()->ofile[fd]) == 0)
    return -1;
@@ -67,7 +78,7 @@ sys_kernlet(int fd, size_t count, off_t off)
    return -1;

  f->ip->ref++;
-  w = pread_allocwork(f->ip, myproc()->vmap->kshared, count, off);
+  w = pread_allocwork(f->ip, count, off, msg, ubuf);
  if (w == NULL) {
    iput(f->ip);
    return -1;
@@ -77,7 +88,7 @@ sys_kernlet(int fd, size_t count, off_t off)
    freework(w);
    return -1;
  }
-  ipc->off = off;
-  ipc->submitted = 1;
+  msg->off = off;
+  msg->submitted = 1;
  return 0;
 }
--- a/preadtest.cc
+++ b/preadtest.cc
+#define PGSIZE 4096
 #include "types.h"
 #include "stat.h"
 #include "fcntl.h"
@@ -19,36 +20,106 @@ static char buf[BSIZE];

 struct ipcctl *ipcctl = (struct ipcctl*)KSHARED;

+static msgid_t
+ipc_msg_alloc(void)
+{
+  if (ipcctl->msghead - ipcctl->msgtail == IPC_NMSG)
+    return NULL_MSGID;
+
+  msgid_t i = ipcctl->msghead % IPC_NMSG;
+  ipcctl->msghead++;
+  return i;
+}
+
+static void
+ipc_msg_free(int msgid)
+{
+  msgid_t i;
+
+  i = ipcctl->msgtail % IPC_NMSG;
+  if (i != msgid)
+    die("ipc_free_msg: oops");
+  ipcctl->msgtail++;
+}
+
+static pageid_t
+ipc_page_alloc(void)
+{
+  if (ipcctl->pagehead - ipcctl->pagetail == IPC_NPAGE)
+    return NULL_PAGEID;
+
+  pageid_t i = ipcctl->pagehead % IPC_NPAGE;
+  ipcctl->pagehead++;
+  return i;
+}
+
+static void
+ipc_page_free(pageid_t pageid)
+{
+  pageid_t i;
+
+  i = ipcctl->pagetail % IPC_NPAGE;
+  if (i != pageid)
+    die("ipc_free_page: oops");
+  ipcctl->pagetail++;
+}
+
 static void
 kernlet_pread(int fd, size_t count, off_t off)
 {
-  ipcctl->done = 0;
-  if (kernlet(fd, count, off) != 0)
+  struct ipcmsg *msg;
+  msgid_t msgid;
+  pageid_t pageid;
+
+  msgid = ipc_msg_alloc();
+  if (msgid == NULL_MSGID) {
+    printf(2, "kernlet_pread: ipc_alloc_msg failed");
+    return;
+  }    
+
+  if (count > PGSIZE)
+    die("kernlet_pread: count oops");
+  pageid = ipc_page_alloc();
+  if (pageid == NULL_PAGEID) {
+    printf(2, "kernlet_pread: ipc_alloc_page failed");
+    return;
+  }
+
+  msg = &ipcctl->msg[msgid];
+  msg->done = 0;
+  msg->pageid = pageid;
+
+  if (kernlet(fd, count, off, msgid, pageid) != 0)
    die("kernlet");
 }

 static ssize_t
 xpread(int fd, void *buf, size_t count, off_t off)
 {
-  if (ipcctl->submitted) {
-    while (ipcctl->done == 0)
+  struct ipcmsg *msg;
+  int msgid;
+
+  msgid = ipcctl->msgtail % IPC_NMSG;
+  msg = &ipcctl->msg[msgid];
+
+  if (msg->submitted) {
+    while (msg->done == 0)
      nop_pause();
-    if (ipcctl->result == -1)
-      goto slow;
-    if (off < ipcctl->off)
-      goto slow;
-    if (off > ipcctl->off + ipcctl->result)
-      goto slow;
+    if (msg->result == -1)
+      die("xpread: result oops");
+    if (msg->off != off)
+      die("xpread: off oops");

-    char *kbuf = (char*) (KSHARED+4096);
-    off_t kbufoff = off - ipcctl->off;
-    size_t kbufcount = MIN(count, ipcctl->result - kbufoff);
+    char *kbuf = (char*) (KSHARED+PGSIZE+(msg->pageid*PGSIZE));
+    off_t kbufoff = off - msg->off;
+    size_t kbufcount = MIN(count, msg->result - kbufoff);

    memmove(buf, kbuf+kbufoff, kbufcount);
+    ipc_msg_free(msgid);
+    ipc_page_free(msg->pageid);
    return kbufcount;
  }

-slow:
  return pread(fd, buf, count, off);
 }

@@ -56,8 +127,10 @@ int
 main(int ac, char **av)
 {
  u64 t0, t1;
-  int i, k;
  int fd;
+  int i;
+
+  memset(ipcctl, 0, sizeof(*ipcctl));

  if (ac > 1)
    usekernlet = av[1][0] == 'k';
@@ -71,12 +144,11 @@ main(int ac, char **av)
      die("write failed");

  t0 = rdtsc();
-  for (k = 0; k < FSIZE; k+=PSIZE) {
-    kernlet_pread(fd, PSIZE, k);
-
-    for (i = k; i < k+PSIZE; i+=BSIZE)
-      if (xpread(fd, buf, BSIZE, i) != BSIZE)
-        die("pread failed");
+  kernlet_pread(fd, BSIZE, 0);
+  for (i = 0; i < FSIZE; i+=BSIZE) {
+    if (xpread(fd, buf, BSIZE, i) != BSIZE)
+      die("pread failed");
+    kernlet_pread(fd, BSIZE, i+BSIZE);
  }
  t1 = rdtsc();


--- a/user.h
+++ b/user.h
 BEGIN_DECLS
 struct stat;
+struct ipcmsg;

 // system calls
 int fork(int);
@@ -27,7 +28,7 @@ int map(void *addr, int len);
 int unmap(void *addr, int len);
 void halt(void);
 ssize_t pread(int, void*, size_t, off_t);
-int kernlet(int, size_t, off_t);
+int kernlet(int, size_t, off_t, u32, u32);

 // ulib.c
 int stat(char*, struct stat*);

--- a/wq.cc
+++ b/wq.cc
@@ -163,8 +163,9 @@ __wq_steal(int c)
 static void
 __wq_run(struct work *w)
 {
-  void (*fn)(struct work*, void*, void*, void*, void*) = (void(*)(work*,void*,void*,void*,void*))w->rip;
-  fn(w, w->arg0, w->arg1, w->arg2, w->arg3);
+  void (*fn)(struct work*, void*, void*, void*, void*, void*) = 
+    (void(*)(work*,void*,void*,void*,void*,void*))w->rip;
+  fn(w, w->arg0, w->arg1, w->arg2, w->arg3, w->arg4);
  freework(w);
 }


--- a/wq.hh
+++ b/wq.hh
@@ -4,5 +4,6 @@ struct work {
  void *arg1;
  void *arg2;
  void *arg3;
+  void *arg4;
  char data[];
 };