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authorrtm <rtm>2006-08-12 17:17:35 +0000
committerrtm <rtm>2006-08-12 17:17:35 +0000
commit14938f9392524ad1b198bf36e63d42e0e61dab85 (patch)
tree762ce608b8d432c1612a4ae3cc6d9698d230cf6b
parent7ce01cf9be997dfec50786b8aec663c84b63c209 (diff)
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buffer cache, fifo replacement
-rw-r--r--Notes3
-rw-r--r--bio.c23
-rw-r--r--buf.h1
-rw-r--r--usertests.c2
4 files changed, 24 insertions, 5 deletions
diff --git a/Notes b/Notes
index 3efafb3..e1d763d 100644
--- a/Notes
+++ b/Notes
@@ -354,3 +354,6 @@ HMM maybe the variables at the end of struct cpu are being overwritten
OH! recursive interrupts will use up any amount of cpu[].stack!
underflow and wrecks *previous* cpu's struct
+
+better buffer cache replacement
+read/write of open file that's been unlinked
diff --git a/bio.c b/bio.c
index 7184a28..2db9694 100644
--- a/bio.c
+++ b/bio.c
@@ -20,20 +20,31 @@ struct buf *
getblk(uint dev, uint sector)
{
struct buf *b;
+ static struct buf *scan = buf;
+ int i;
acquire(&buf_table_lock);
while(1){
for(b = buf; b < buf+NBUF; b++)
- if((b->flags & B_BUSY) && b->dev == dev && b->sector)
+ if((b->flags & (B_BUSY|B_VALID)) && b->dev == dev && b->sector == sector)
break;
if(b < buf+NBUF){
- sleep(buf, &buf_table_lock);
+ if(b->flags & B_BUSY){
+ sleep(buf, &buf_table_lock);
+ } else {
+ b->flags |= B_BUSY;
+ release(&buf_table_lock);
+ return b;
+ }
} else {
- for(b = buf; b < buf+NBUF; b++){
+ for(i = 0; i < NBUF; i++){
+ b = scan++;
+ if(scan >= buf+NBUF)
+ scan = buf;
if((b->flags & B_BUSY) == 0){
- b->flags |= B_BUSY;
+ b->flags = B_BUSY;
b->dev = dev;
b->sector = sector;
release(&buf_table_lock);
@@ -53,11 +64,14 @@ bread(uint dev, uint sector)
extern struct spinlock ide_lock;
b = getblk(dev, sector);
+ if(b->flags & B_VALID)
+ return b;
acquire(&ide_lock);
c = ide_start_rw(dev & 0xff, sector, b->data, 1, 1);
sleep (c, &ide_lock);
ide_finish(c);
+ b->flags |= B_VALID;
release(&ide_lock);
return b;
@@ -73,6 +87,7 @@ bwrite(uint dev, struct buf *b, uint sector)
c = ide_start_rw(dev & 0xff, sector, b->data, 1, 0);
sleep (c, &ide_lock);
ide_finish(c);
+ b->flags |= B_VALID;
release(&ide_lock);
}
diff --git a/buf.h b/buf.h
index e3f6b14..7ab352a 100644
--- a/buf.h
+++ b/buf.h
@@ -5,3 +5,4 @@ struct buf {
uchar data[512];
};
#define B_BUSY 0x1
+#define B_VALID 0x2
diff --git a/usertests.c b/usertests.c
index a3bb284..9bd144c 100644
--- a/usertests.c
+++ b/usertests.c
@@ -339,7 +339,7 @@ main(int argc, char *argv[])
{
puts("usertests starting\n");
- unlinkread();
+ //unlinkread();
createdelete();
twofiles();
sharedfd();