checkpoint for lock lab

gradelib.py

@@ -238,7 +238,7 @@ def make(*target):
     post_make()
 
 def show_command(cmd):
-    from shlex import quote
+    from pipes import quote
     print("\n$", " ".join(map(quote, cmd)))
 
 def maybe_unlink(*paths):

kernel/bio.c

@@ -23,129 +23,32 @@
 #include "fs.h"
 #include "buf.h"
 
-
-// TODO: use sleeplock instead of spinlock
-
 struct {
   struct spinlock lock;
   struct buf buf[NBUF];
-  #define NHASH 233
-  // struct hash_t{
-  //   uint pos;
-  //   struct hash_t *nxt;
-  // }hash[NHASH];
-  uint hash_head[NHASH];
-  uint nxt[NBUF];
-  struct spinlock hashlock[NHASH];
-  uint freelist_head[NCPU];
+
   // Linked list of all buffers, through prev/next.
   // Sorted by how recently the buffer was used.
   // head.next is most recent, head.prev is least.
-  // struct buf head;
-  struct spinlock freelistlock[NCPU];
+  struct buf head;
 } bcache;
 
-uint hasher(uint dev,uint blockno){
-  return ((uint64)dev<<32|blockno)%NHASH;
-}
-
-int hash_get(uint dev,uint blockno){
-  const uint hash_pos=hasher(dev, blockno);
-  int pos=-1;
-  // acquire(&bcache.hashlock[hash_pos]);
-  for(int cur=bcache.hash_head[hash_pos];cur!=-1;cur=bcache.nxt[cur])
-    if(bcache.buf[cur].dev==dev && bcache.buf[cur].blockno==blockno){
-      pos=cur;
-      goto RET;
-    }
-  
-  RET:
-
-  // release(&bcache.hashlock[hash_pos]);
-  // printf("%u\n",pos);
-  return pos;
-}
-
-void hash_add(uint dev,uint blockno,uint buf_pos){
-  const uint hash_pos=hasher(dev, blockno);
-  // acquire(&bcache.hashlock[hash_pos]);
-  bcache.nxt[buf_pos]=bcache.hash_head[hash_pos];
-  bcache.hash_head[hash_pos]=buf_pos;
-  // release(&bcache.hashlock[hash_pos]);
-}
-
-void hash_del(uint dev,uint blockno){
-  const uint hash_pos=hasher(dev, blockno);
-  push_off();
-  const uint cpu=cpuid();
-  pop_off();
-  acquire(&bcache.hashlock[hash_pos]);
-  for(int cur=bcache.hash_head[hash_pos],pre=-2;cur!=-1;cur=bcache.nxt[cur]){
-      if(bcache.buf[cur].dev==dev && bcache.buf[cur].blockno==blockno){
-        struct buf *b=&bcache.buf[cur];
-        --b->refcnt;
-        if (b->refcnt == 0) {
-          if(pre==-2){// the head is what we are looking for
-            bcache.hash_head[hash_pos]=bcache.nxt[cur];
-          }else{
-            bcache.nxt[pre]=bcache.nxt[cur];
-          }
-          bcache.nxt[cur]=-1;
-          for(int i=cpu;;i=(i+1)%NCPU){
-            push_off();
-            if(holding(&bcache.freelistlock[i])){
-              pop_off();
-              continue;
-            }
-            pop_off();
-            acquire(&bcache.freelistlock[i]);
-            const int pos=b-bcache.buf;
-            // printf("%d\n",pos);
-            bcache.nxt[pos]=bcache.freelist_head[i];
-            bcache.freelist_head[i]=pos;
-
-            // DEBUG();
-            // printf("%u\n",bcache.freelist_head);
-
-            release(&bcache.freelistlock[i]);
-            break;
-          }
-          break;
-        }
-      }
-      pre=cur;
-  }
-  release(&bcache.hashlock[hash_pos]);
-}
-
 void
 binit(void)
 {
   struct buf *b;
 
   initlock(&bcache.lock, "bcache");
-  for(int i=0;i<NHASH;i++){
-    initlock(&bcache.hashlock[i], "bcache_hashtable");
-    bcache.hash_head[i]=-1;
-  }
-  for(int i=0;i<NCPU;++i){
-    bcache.freelist_head[i]=-1;
-    initlock(&bcache.freelistlock[i], "bcache_freelist");
-  }
+
   // Create linked list of buffers
-  // bcache.head.prev = &bcache.head;
-  // bcache.head.next = &bcache.head;
-  int which=0;
+  bcache.head.prev = &bcache.head;
+  bcache.head.next = &bcache.head;
   for(b = bcache.buf; b < bcache.buf+NBUF; b++){
-    // b->next = bcache.head.next;
-    // b->prev = &bcache.head;
+    b->next = bcache.head.next;
+    b->prev = &bcache.head;
     initsleeplock(&b->lock, "buffer");
-    const uint cur=b-bcache.buf;
-    bcache.nxt[cur]=bcache.freelist_head[which];
-    bcache.freelist_head[which]=cur;
-    which=(which+1)%NCPU;
-    // bcache.head.next->prev = b;
-    // bcache.head.next = b;
+    bcache.head.next->prev = b;
+    bcache.head.next = b;
   }
 }
 
@@ -156,74 +59,31 @@ static struct buf*
 bget(uint dev, uint blockno)
 {
   struct buf *b;
-  // acquire(&bcache.lock);
-    const uint hash_pos=hasher(dev, blockno);
-  acquire(&bcache.hashlock[hash_pos]);
-  const int pos=hash_get(dev, blockno);
+
+  acquire(&bcache.lock);
+
   // Is the block already cached?
-  // for(b = bcache.head.next; b != &bcache.head; b = b->next){
-  //   if(b->dev == dev && b->blockno == blockno){
-  //     b->refcnt++;
-  //     release(&bcache.lock);
-  //     acquiresleep(&b->lock);
-  //     return b;
-  //   }
-  // }
-  if(pos>=0){
-    b=&bcache.buf[pos];
-    // acquire(&bcache.hashlock[hash_pos]);
-    ++bcache.buf[pos].refcnt;
-    release(&bcache.hashlock[hash_pos]);
-    acquiresleep(&b->lock);
-    // release(&bcache.lock);
-    return b;
+  for(b = bcache.head.next; b != &bcache.head; b = b->next){
+    if(b->dev == dev && b->blockno == blockno){
+      b->refcnt++;
+      release(&bcache.lock);
+      acquiresleep(&b->lock);
+      return b;
+    }
   }
-  push_off();
-  const uint cpu=cpuid();
-  pop_off();
+
   // Not cached.
   // Recycle the least recently used (LRU) unused buffer.
-  for(int i=cpu;;i=(i+1)%NCPU){
-    push_off();
-    if(holding(&bcache.freelistlock[i])){
-      pop_off();
-      continue;
+  for(b = bcache.head.prev; b != &bcache.head; b = b->prev){
+    if(b->refcnt == 0) {
+      b->dev = dev;
+      b->blockno = blockno;
+      b->valid = 0;
+      b->refcnt = 1;
+      release(&bcache.lock);
+      acquiresleep(&b->lock);
+      return b;
     }
-    pop_off();
-    acquire(&bcache.freelistlock[i]);
-    if(bcache.freelist_head[i]==-1){
-        release(&bcache.freelistlock[i]);
-        continue;
-    }
-    // DEBUG();
-    // for(b = bcache.head.prev; b != &bcache.head; b = b->prev){
-    //   if(b->refcnt == 0) {
-    //     hash_add(dev, blockno, b-bcache.buf);
-    //     b->dev = dev;
-    //     b->blockno = blockno;
-    //     b->valid = 0;
-    //     b->refcnt = 1;
-    //     release(&bcache.lock);
-    //     acquiresleep(&b->lock);
-    //     return b;
-    //   }
-    // }
-    // for(uint cur=bcache.freelist_head;cur!=-1;cur=bcache.nxt[cur])
-    // DEBUG();
-    // printf("%u\n",bcache.freelist_head);
-    b=&bcache.buf[bcache.freelist_head[i]];
-    const int ori=bcache.freelist_head[i];
-    bcache.freelist_head[i]=bcache.nxt[bcache.freelist_head[i]];
-    hash_add(dev,blockno,ori);
-    release(&bcache.hashlock[hash_pos]);    
-    b->dev=dev;
-    b->blockno=blockno;
-    b->valid=0;
-    b->refcnt=1;
-    release(&bcache.freelistlock[i]);
-    acquiresleep(&b->lock);
-    // release(&bcache.lock);
-    return b;
   }
   panic("bget: no buffers");
 }
@@ -256,46 +116,38 @@ bwrite(struct buf *b)
 void
 brelse(struct buf *b)
 {
-
   if(!holdingsleep(&b->lock))
     panic("brelse");
 
   releasesleep(&b->lock);
 
-  // acquire(&bcache.lock);
-  
-  hash_del(b->dev, b->blockno);
+  acquire(&bcache.lock);
+  b->refcnt--;
+  if (b->refcnt == 0) {
     // no one is waiting for it.
-    // b->next->prev = b->prev;
-    // b->prev->next = b->next;
-    // b->next = bcache.head.next;
-    // b->prev = &bcache.head;
-    // bcache.head.next->prev = b;
-    // bcache.head.next = b;gi
-
+    b->next->prev = b->prev;
+    b->prev->next = b->next;
+    b->next = bcache.head.next;
+    b->prev = &bcache.head;
+    bcache.head.next->prev = b;
+    bcache.head.next = b;
+  }
   
-  
-  // release(&bcache.lock);
+  release(&bcache.lock);
 }
 
 void
 bpin(struct buf *b) {
-  // acquire(&bcache.lock);
-  const uint hash_pos=hasher(b->dev, b->blockno);
-  acquire(&bcache.hashlock[hash_pos]);
+  acquire(&bcache.lock);
   b->refcnt++;
-  release(&bcache.hashlock[hash_pos]);
-  // release(&bcache.lock);
+  release(&bcache.lock);
 }
 
 void
 bunpin(struct buf *b) {
-  // acquire(&bcache.lock);
-  const uint hash_pos=hasher(b->dev, b->blockno);
-  acquire(&bcache.hashlock[hash_pos]);
+  acquire(&bcache.lock);
   b->refcnt--;
-  release(&bcache.hashlock[hash_pos]);
-  // release(&bcache.lock);
+  release(&bcache.lock);
 }
 
 

kernel/buf.h

@@ -5,8 +5,8 @@ struct buf {
   uint blockno;
   struct sleeplock lock;
   uint refcnt;
-  // struct buf *prev; // LRU cache list
-  // struct buf *next;
+  struct buf *prev; // LRU cache list
+  struct buf *next;
   uchar data[BSIZE];
 };
 

kernel/defs.h

@@ -237,4 +237,3 @@ void            netinit(void);
 void            net_rx(char *buf, int len);
 
 #endif
-#define DEBUG() printf("File: %s, Line: %d, Function: %s\n", __FILE__, __LINE__, __func__)

kernel/fs.c

@@ -93,14 +93,12 @@ bfree(int dev, uint b)
 {
   struct buf *bp;
   int bi, m;
-  // DEBUG();
-  // printf("%d %d\n",dev,b);
+
   bp = bread(dev, BBLOCK(b, sb));
   bi = b % BPB;
   m = 1 << (bi % 8);
-  if((bp->data[bi/8] & m) == 0){
+  if((bp->data[bi/8] & m) == 0)
     panic("freeing free block");
-  }
   bp->data[bi/8] &= ~m;
   log_write(bp);
   brelse(bp);

kernel/kalloc.c

@@ -21,13 +21,12 @@ struct run {
 struct {
   struct spinlock lock;
   struct run *freelist;
-} kmem[NCPU];
+} kmem;
 
-void 
+void
 kinit()
 {
-  for(int i=0;i<NCPU;++i)
-    initlock(&kmem[i].lock, "kmem");
+  initlock(&kmem.lock, "kmem");
   freerange(end, (void*)PHYSTOP);
 }
 
@@ -48,7 +47,6 @@ void
 kfree(void *pa)
 {
   struct run *r;
-  int id;
 
   if(((uint64)pa % PGSIZE) != 0 || (char*)pa < end || (uint64)pa >= PHYSTOP)
     panic("kfree");
@@ -57,20 +55,11 @@ kfree(void *pa)
   memset(pa, 1, PGSIZE);
 
   r = (struct run*)pa;
-  
-  push_off();
-  id = cpuid();
-  pop_off();
-  
-  acquire(&kmem[id].lock);
-  r->next = kmem[id].freelist;
-  kmem[id].freelist = r;
-  release(&kmem[id].lock);
 
-  /*acquire(&kmem.lock);
+  acquire(&kmem.lock);
   r->next = kmem.freelist;
   kmem.freelist = r;
-  release(&kmem.lock);*/
+  release(&kmem.lock);
 }
 
 // Allocate one 4096-byte page of physical memory.
@@ -80,37 +69,13 @@ void *
 kalloc(void)
 {
   struct run *r;
-  int id;
 
-  push_off();
-  id = cpuid();
-  pop_off();
-
-  acquire(&kmem[id].lock);
-  r = kmem[id].freelist;
-  if (r)
-    kmem[id].freelist = r->next;
-  release(&kmem[id].lock);
-  if (r)
-    goto kallocinit;
-
-  for (int i=(id+1)%NCPU; i!=id; i=(i+1)%NCPU) {
-    acquire(&kmem[i].lock);
-    r = kmem[i].freelist;
-    if (r)
-      kmem[i].freelist = r->next;
-    release(&kmem[i].lock);
-    if (r)
-      goto kallocinit;
-  }
-
-  /*acquire(&kmem.lock);
+  acquire(&kmem.lock);
   r = kmem.freelist;
   if(r)
     kmem.freelist = r->next;
-  release(&kmem.lock);*/
+  release(&kmem.lock);
 
-kallocinit:
   if(r)
     memset((char*)r, 5, PGSIZE); // fill with junk
   return (void*)r;

time.txt

@@ -1 +0,0 @@
-6

user/kalloctest.c

@@ -168,7 +168,7 @@ void test3(void)
   kill(pid);
 
   n = ntas(1);
-  if(n-m < 10000) 
+  if(n-m < 4000) 
     printf("\ntest3 OK\n");
   else
     printf("test3 FAIL m %d n %d\n", m, n);