Skip to content

X
xv6-public
提交 d564ca3d 创建 作者: Nickolai Zeldovich's avatar Nickolai Zeldovich
浏览文件
操作

ditch bcache refcounts, use rcu

上级 ae6af083
隐藏空白字符变更
内嵌 并排
正在显示 包含 64 行增加 和 49 行删除
bio.c
浏览文件 @ d564ca3d
......@@ -54,7 +54,7 @@ evict(uint key, void *bp)
{
struct buf *b = bp;
acquire(&b->lock);
if ((b->flags & (B_BUSYR | B_BUSYW | B_VALID)) == 0)
if ((b->flags & (B_BUSY | B_VALID)) == 0)
return b;
release(&b->lock);
return 0;
......@@ -65,7 +65,7 @@ evict_valid(uint key, void *bp)
{
struct buf *b = bp;
acquire(&b->lock);
if ((b->flags & (B_BUSYR | B_BUSYW)) == 0)
if ((b->flags & (B_BUSY)) == 0)
return b;
release(&b->lock);
return 0;
......@@ -75,7 +75,7 @@ evict_valid(uint key, void *bp)
// If not found, allocate fresh block.
// In either case, return locked buffer.
static struct buf*
bget(uint dev, uint sector, int writer)
bget(uint dev, uint sector, int *writer)
{
struct buf *b;
......@@ -85,21 +85,24 @@ bget(uint dev, uint sector, int writer)
rcu_begin_read();
b = ns_lookup(bufns, sector);
if (b) {
acquire(&b->lock);
if (b->dev != dev)
panic("dev mismatch");
if (!(b->flags & (B_BUSYW | (writer ? B_BUSYR : 0)))) {
b->flags |= B_BUSYR | (writer ? B_BUSYW : 0);
__sync_fetch_and_add(&b->readbusy, 1);
if (*writer || !(b->flags & B_VALID)) {
acquire(&b->lock);
if (b->flags & B_BUSY) {
cv_sleep(&b->cv, &b->lock);
release(&b->lock);
rcu_end_read();
goto loop;
}
b->flags |= B_BUSY;
release(&b->lock);
rcu_end_read();
return b;
*writer = 1;
}
cv_sleep(&b->cv, &b->lock);
release(&b->lock);
rcu_end_read();
goto loop;
// rcu_end_read() happens in brelse
return b;
}
rcu_end_read();
......@@ -109,8 +112,7 @@ bget(uint dev, uint sector, int writer)
victim = ns_enumerate(bufns, evict_valid);
if (victim == 0)
panic("bget all busy");
victim->flags |= B_BUSYR | B_BUSYW;
__sync_fetch_and_add(&victim->readbusy, 1);
victim->flags |= B_BUSY;
ns_remove(bufns, victim->sector, victim);
release(&victim->lock);
rcu_delayed(victim, kmfree);
......@@ -118,15 +120,17 @@ bget(uint dev, uint sector, int writer)
b = kmalloc(sizeof(*b));
b->dev = dev;
b->sector = sector;
b->flags = B_BUSYR | B_BUSYW;
b->readbusy = 1;
b->flags = B_BUSY;
*writer = 1;
snprintf(b->lockname, sizeof(b->lockname), "cv:buf:%d", b->sector);
initlock(&b->lock, b->lockname+3);
initcondvar(&b->cv, b->lockname);
rcu_begin_read();
if (ns_insert(bufns, b->sector, b) < 0) {
rcu_delayed(b, kmfree);
goto loop;
}
// rcu_end_read() happens in brelse
return b;
}
......@@ -136,9 +140,15 @@ bread(uint dev, uint sector, int writer)
{
struct buf *b;
b = bget(dev, sector, writer);
int origwriter = writer;
b = bget(dev, sector, &writer);
if(!(b->flags & B_VALID))
iderw(b);
if (writer && !origwriter) {
acquire(&b->lock);
b->flags &= ~B_BUSY;
release(&b->lock);
}
return b;
}
......@@ -146,7 +156,7 @@ bread(uint dev, uint sector, int writer)
void
bwrite(struct buf *b)
{
if((b->flags & B_BUSYW) == 0)
if((b->flags & B_BUSY) == 0)
panic("bwrite");
b->flags |= B_DIRTY;
if (writeback)
......@@ -155,14 +165,17 @@ bwrite(struct buf *b)
// Release the buffer b.
void
brelse(struct buf *b)
brelse(struct buf *b, int writer)
{
acquire(&b->lock);
if((b->flags & (B_BUSYR | B_BUSYW)) == 0)
panic("brelse");
int lastreader = __sync_sub_and_fetch(&b->readbusy, 1);
b->flags &= ~(B_BUSYW | ((lastreader==0) ? B_BUSYR : 0));
release(&b->lock);
cv_wakeup(&b->cv);
if (writer) {
acquire(&b->lock);
if((b->flags & B_BUSY) == 0)
panic("brelse");
b->flags &= ~B_BUSY;
release(&b->lock);
cv_wakeup(&b->cv);
}
// rcu_begin_read() happens in bread
rcu_end_read();
}
buf.h
浏览文件 @ d564ca3d
......@@ -2,7 +2,6 @@ struct buf {
int flags;
uint dev;
uint sector;
int readbusy;
struct buf *prev; // LRU cache list
struct buf *next;
struct buf *qnext; // disk queue
......@@ -11,8 +10,7 @@ struct buf {
struct spinlock lock;
uchar data[512];
};
#define B_BUSYR 0x1 // buffer is locked by some process
#define B_BUSYW 0x2 // buffer is locked by some process
#define B_VALID 0x4 // buffer has been read from disk
#define B_DIRTY 0x8 // buffer needs to be written to disk
#define B_BUSY 0x1 // buffer is locked by some process
#define B_VALID 0x2 // buffer has been read from disk
#define B_DIRTY 0x4 // buffer needs to be written to disk
condvar.c
浏览文件 @ d564ca3d
......@@ -52,6 +52,9 @@ cv_sleep(struct condvar *cv, struct spinlock *lk)
void
cv_wakeup(struct condvar *cv)
{
if (!cv->waiters)
return;
acquire(&cv->lock);
while(cv->waiters) {
struct proc *p = cv->waiters;
......
defs.h
浏览文件 @ d564ca3d
......@@ -15,7 +15,7 @@ struct ns;
// bio.c
void binit(void);
struct buf* bread(uint, uint, int writer);
void brelse(struct buf*);
void brelse(struct buf*, int writer);
void bwrite(struct buf*);
// condvar.c
......
fs.c
浏览文件 @ d564ca3d
......@@ -34,7 +34,7 @@ readsb(int dev, struct superblock *sb)
bp = bread(dev, 1, 0);
memmove(sb, bp->data, sizeof(*sb));
brelse(bp);
brelse(bp, 0);
}
// Zero a block.
......@@ -46,7 +46,7 @@ bzero(int dev, int bno)
bp = bread(dev, bno, 1);
memset(bp->data, 0, BSIZE);
bwrite(bp);
brelse(bp);
brelse(bp, 1);
}
// Blocks.
......@@ -68,11 +68,11 @@ balloc(uint dev)
if((bp->data[bi/8] & m) == 0){ // Is block free?
bp->data[bi/8] |= m; // Mark block in use on disk.
bwrite(bp);
brelse(bp);
brelse(bp, 1);
return b + bi;
}
}
brelse(bp);
brelse(bp, 1);
}
panic("balloc: out of blocks");
}
......@@ -95,7 +95,7 @@ bfree(int dev, uint b)
panic("freeing free block");
bp->data[bi/8] &= ~m; // Mark block free on disk.
bwrite(bp);
brelse(bp);
brelse(bp, 1);
}
// Inodes.
......@@ -160,10 +160,10 @@ ialloc(uint dev, short type)
readsb(dev, &sb);
for(inum = 1; inum < sb.ninodes; inum++){ // loop over inode blocks
bp = bread(dev, IBLOCK(inum), 1);
bp = bread(dev, IBLOCK(inum), 0);
dip = (struct dinode*)bp->data + inum%IPB;
int seemsfree = (dip->type == 0);
brelse(bp);
brelse(bp, 0);
if(seemsfree){
// maybe this inode is free. look at it via the
// inode cache to make sure.
......@@ -201,7 +201,7 @@ iupdate(struct inode *ip)
dip->gen = ip->gen;
memmove(dip->addrs, ip->addrs, sizeof(ip->addrs));
bwrite(bp);
brelse(bp);
brelse(bp, 1);
}
static void *
......@@ -277,7 +277,7 @@ iget(uint dev, uint inum)
ip->size = dip->size;
ip->gen = dip->gen;
memmove(ip->addrs, dip->addrs, sizeof(ip->addrs));
brelse(bp);
brelse(bp, 0);
ip->flags |= I_VALID;
iunlock(ip);
......@@ -400,7 +400,7 @@ bmap(struct inode *ip, uint bn)
a[bn] = addr = balloc(ip->dev);
bwrite(bp);
}
brelse(bp);
brelse(bp, 1);
return addr;
}
......@@ -431,7 +431,7 @@ itrunc(struct inode *ip)
if(a[j])
bfree(ip->dev, a[j]);
}
brelse(bp);
brelse(bp, 0);
bfree(ip->dev, ip->addrs[NDIRECT]);
ip->addrs[NDIRECT] = 0;
}
......@@ -474,7 +474,7 @@ readi(struct inode *ip, char *dst, uint off, uint n)
bp = bread(ip->dev, bmap(ip, off/BSIZE), 0);
m = min(n - tot, BSIZE - off%BSIZE);
memmove(dst, bp->data + off%BSIZE, m);
brelse(bp);
brelse(bp, 0);
}
return n;
}
......@@ -503,7 +503,7 @@ writei(struct inode *ip, char *src, uint off, uint n)
m = min(n - tot, BSIZE - off%BSIZE);
memmove(bp->data + off%BSIZE, src, m);
bwrite(bp);
brelse(bp);
brelse(bp, 1);
}
if(n > 0 && off > ip->size){
......@@ -547,11 +547,11 @@ dirlookup(struct inode *dp, char *name, uint *poff)
if(poff)
*poff = off + (uchar*)de - bp->data;
inum = de->inum;
brelse(bp);
brelse(bp, 0);
return iget(dp->dev, inum);
}
}
brelse(bp);
brelse(bp, 0);
}
return 0;
}
......
ide.c
浏览文件 @ d564ca3d
......@@ -130,7 +130,7 @@ iderw(struct buf *b)
{
struct buf **pp;
if(!(b->flags & (B_BUSYR | B_BUSYW)))
if(!(b->flags & B_BUSY))
panic("iderw: buf not busy");
if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
panic("iderw: nothing to do");
......
main.c
浏览文件 @ d564ca3d
......@@ -62,6 +62,7 @@ mainc(void)
ideinit(); // disk
if(!ismp)
timerinit(); // uniprocessor timer
nc_init();
userinit(); // first user process
bootothers(); // start other processors
kvmalloc(); // new kernel page table wo. bottom mapped
......
您添加了 0 人 到此讨论。请谨慎行事。
请先完成此评论的编辑！
请 注册 或者 后发表评论