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i think this is a working concurrent logging scheme
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Robert Morris committed Aug 28, 2014
1 parent 71453f7 commit 48aa917
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Showing 5 changed files with 113 additions and 95 deletions.
2 changes: 2 additions & 0 deletions bio.c
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Expand Up @@ -80,6 +80,8 @@ bget(uint dev, uint sector)
}

// Not cached; recycle some non-busy and clean buffer.
// "clean" because B_DIRTY and !B_BUSY means log.c
// hasn't yet committed the changes to the buffer.
for(b = bcache.head.prev; b != &bcache.head; b = b->prev){
if((b->flags & B_BUSY) == 0 && (b->flags & B_DIRTY) == 0){
b->dev = dev;
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21 changes: 19 additions & 2 deletions log.c
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Expand Up @@ -52,6 +52,10 @@ struct log log;
static void recover_from_log(void);
static void commit();

// statistics, delete eventually XXX.
static int maxsize;
static int maxoutstanding;

void
initlog(void)
{
Expand Down Expand Up @@ -131,10 +135,15 @@ begin_op(void)
while(1){
if(log.committing){
sleep(&log, &log.lock);
} else if(log.lh.n + (log.outstanding+1)*MAXOPBLOCKS > LOGSIZE){
// this op might exhaust log space; wait for commit.
sleep(&log, &log.lock);
} else {
// XXX wait (for a commit) if log is longish.
// need to reserve to avoid over-commit of log space.
log.outstanding += 1;
if(log.outstanding > maxoutstanding){
maxoutstanding = log.outstanding;
cprintf("%d outstanding\n", log.outstanding);
}
release(&log.lock);
break;
}
Expand All @@ -155,6 +164,9 @@ end_op(void)
if(log.outstanding == 0){
do_commit = 1;
log.committing = 1;
} else {
// begin_op() may be waiting for log space.
wakeup(&log);
}
release(&log.lock);

Expand Down Expand Up @@ -208,6 +220,11 @@ log_write(struct buf *b)
if (i == log.lh.n)
log.lh.n++;
b->flags |= B_DIRTY; // XXX prevent eviction

if(log.lh.n > maxsize){
maxsize = log.lh.n;
cprintf("log size %d/%d\n", log.lh.n, LOGSIZE);
}
}

//PAGEBREAK!
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2 changes: 1 addition & 1 deletion mkfs.c
View file
Expand Up @@ -13,7 +13,7 @@

#define static_assert(a, b) do { switch (0) case 0: case (a): ; } while (0)

int nblocks = 985;
int nblocks = (995-LOGSIZE);
int nlog = LOGSIZE;
int ninodes = 200;
int size = 1024;
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5 changes: 3 additions & 2 deletions param.h
View file
Expand Up @@ -3,10 +3,11 @@
#define NCPU 8 // maximum number of CPUs
#define NOFILE 16 // open files per process
#define NFILE 100 // open files per system
#define NBUF 10 // size of disk block cache
#define NINODE 50 // maximum number of active i-nodes
#define NDEV 10 // maximum major device number
#define ROOTDEV 1 // device number of file system root disk
#define MAXARG 32 // max exec arguments
#define LOGSIZE 10 // max data sectors in on-disk log
#define MAXOPBLOCKS 10 // max # of blocks any FS op writes
#define LOGSIZE (MAXOPBLOCKS*3) // max data sectors in on-disk log
#define NBUF (MAXOPBLOCKS*3) // size of disk block cache (>= LOGSIZE)

178 changes: 88 additions & 90 deletions usertests.c
View file
Expand Up @@ -512,51 +512,56 @@ sharedfd(void)
}
}

// two processes write two different files at the same
// four processes write different files at the same
// time, to test block allocation.
void
twofiles(void)
fourfiles(void)
{
int fd, pid, i, j, n, total;
int fd, pid, i, j, n, total, pi;
char *names[] = { "f0", "f1", "f2", "f3" };
char *fname;

printf(1, "twofiles test\n");
printf(1, "fourfiles test\n");

unlink("f1");
unlink("f2");
for(pi = 0; pi < 4; pi++){
fname = names[pi];
unlink(fname);

pid = fork();
if(pid < 0){
printf(1, "fork failed\n");
exit();
}

fname = pid ? "f1" : "f2";
fd = open(fname, O_CREATE | O_RDWR);
if(fd < 0){
printf(1, "create failed\n");
exit();
}
pid = fork();
if(pid < 0){
printf(1, "fork failed\n");
exit();
}

memset(buf, pid?'p':'c', 512);
for(i = 0; i < 12; i++){
if((n = write(fd, buf, 500)) != 500){
printf(1, "write failed %d\n", n);
if(pid == 0){
fd = open(fname, O_CREATE | O_RDWR);
if(fd < 0){
printf(1, "create failed\n");
exit();
}

memset(buf, '0'+pi, 512);
for(i = 0; i < 12; i++){
if((n = write(fd, buf, 500)) != 500){
printf(1, "write failed %d\n", n);
exit();
}
}
exit();
}
}
close(fd);
if(pid)

for(pi = 0; pi < 4; pi++){
wait();
else
exit();
}

for(i = 0; i < 2; i++){
fd = open(i?"f1":"f2", 0);
fname = names[i];
fd = open(fname, 0);
total = 0;
while((n = read(fd, buf, sizeof(buf))) > 0){
for(j = 0; j < n; j++){
if(buf[j] != (i?'p':'c')){
if(buf[j] != '0'+i){
printf(1, "wrong char\n");
exit();
}
Expand All @@ -568,87 +573,80 @@ twofiles(void)
printf(1, "wrong length %d\n", total);
exit();
}
unlink(fname);
}

unlink("f1");
unlink("f2");

printf(1, "twofiles ok\n");
printf(1, "fourfiles ok\n");
}

// two processes create and delete different files in same directory
// four processes create and delete different files in same directory
void
createdelete(void)
{
enum { N = 20 };
int pid, i, fd;
int pid, i, fd, pi;
char name[32];

printf(1, "createdelete test\n");
pid = fork();
if(pid < 0){
printf(1, "fork failed\n");
exit();
}

name[0] = pid ? 'p' : 'c';
name[2] = '\0';
for(i = 0; i < N; i++){
name[1] = '0' + i;
fd = open(name, O_CREATE | O_RDWR);
if(fd < 0){
printf(1, "create failed\n");
for(pi = 0; pi < 4; pi++){
pid = fork();
if(pid < 0){
printf(1, "fork failed\n");
exit();
}
close(fd);
if(i > 0 && (i % 2 ) == 0){
name[1] = '0' + (i / 2);
if(unlink(name) < 0){
printf(1, "unlink failed\n");
exit();

if(pid == 0){
name[0] = 'p' + pi;
name[2] = '\0';
for(i = 0; i < N; i++){
name[1] = '0' + i;
fd = open(name, O_CREATE | O_RDWR);
if(fd < 0){
printf(1, "create failed\n");
exit();
}
close(fd);
if(i > 0 && (i % 2 ) == 0){
name[1] = '0' + (i / 2);
if(unlink(name) < 0){
printf(1, "unlink failed\n");
exit();
}
}
}
exit();
}
}

if(pid==0)
exit();
else
for(pi = 0; pi < 4; pi++){
wait();
}

name[0] = name[1] = name[2] = 0;
for(i = 0; i < N; i++){
name[0] = 'p';
name[1] = '0' + i;
fd = open(name, 0);
if((i == 0 || i >= N/2) && fd < 0){
printf(1, "oops createdelete %s didn't exist\n", name);
exit();
} else if((i >= 1 && i < N/2) && fd >= 0){
printf(1, "oops createdelete %s did exist\n", name);
exit();
}
if(fd >= 0)
close(fd);

name[0] = 'c';
name[1] = '0' + i;
fd = open(name, 0);
if((i == 0 || i >= N/2) && fd < 0){
printf(1, "oops createdelete %s didn't exist\n", name);
exit();
} else if((i >= 1 && i < N/2) && fd >= 0){
printf(1, "oops createdelete %s did exist\n", name);
exit();
for(pi = 0; pi < 4; pi++){
name[0] = 'p' + pi;
name[1] = '0' + i;
fd = open(name, 0);
if((i == 0 || i >= N/2) && fd < 0){
printf(1, "oops createdelete %s didn't exist\n", name);
exit();
} else if((i >= 1 && i < N/2) && fd >= 0){
printf(1, "oops createdelete %s did exist\n", name);
exit();
}
if(fd >= 0)
close(fd);
}
if(fd >= 0)
close(fd);
}

for(i = 0; i < N; i++){
name[0] = 'p';
name[1] = '0' + i;
unlink(name);
name[0] = 'c';
unlink(name);
for(pi = 0; pi < 4; pi++){
name[0] = 'p' + i;
name[1] = '0' + i;
unlink(name);
}
}

printf(1, "createdelete ok\n");
Expand Down Expand Up @@ -1716,6 +1714,12 @@ main(int argc, char *argv[])
}
close(open("usertests.ran", O_CREATE));

createdelete();
linkunlink();
concreate();
fourfiles();
sharedfd();

bigargtest();
bigwrite();
bigargtest();
Expand All @@ -1741,18 +1745,12 @@ main(int argc, char *argv[])
fourteen();
bigfile();
subdir();
concreate();
linkunlink();
linktest();
unlinkread();
createdelete();
twofiles();
sharedfd();
dirfile();
iref();
forktest();
bigdir(); // slow

exectest();

exit();
Expand Down

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