libc: change tas/sleep locks to cas/semacquire/semrelease locks (from sources)

spinlocks have been changed to use the new semacquire/semrelease
syscalls in combination with atomic compare and swap operations.

5 files changed, 66 insertions, 76 deletions

diff --git a/sys/src/libc/port/cycles.c b/sys/src/libc/port/cycles.c
new file mode 100644
index 000000000..9bad3a989
--- /dev/null
+++ b/sys/src/libc/port/cycles.c
@@ -0,0 +1,7 @@
+#include <u.h>
+#include <libc.h>
+
+void	cycles(uvlong*u)
+{
+	*u = 0LL;
+}
diff --git a/sys/src/libc/port/lock.c b/sys/src/libc/port/lock.c
index af07b9cc7..213fcd778 100644
--- a/sys/src/libc/port/lock.c
+++ b/sys/src/libc/port/lock.c
@@ -2,40 +2,32 @@
 #include <libc.h>
 
 void
-lock(Lock *lk)
+lock(Lock *l)
 {
-	int i;
-
-	/* once fast */
-	if(!_tas(&lk->val))
-		return;
-	/* a thousand times pretty fast */
-	for(i=0; i<1000; i++){
-		if(!_tas(&lk->val))
-			return;
-		sleep(0);
-	}
-	/* now nice and slow */
-	for(i=0; i<1000; i++){
-		if(!_tas(&lk->val))
-			return;
-		sleep(100);
+	if(ainc(&l->key) == 1)
+		return;	/* changed from 0 -> 1: we hold lock */
+	/* otherwise wait in kernel */
+	while(semacquire(&l->sem, 1) < 0){
+		/* interrupted; try again */
 	}
-	/* take your time */
-	while(_tas(&lk->val))
-		sleep(1000);
 }
 
-int
-canlock(Lock *lk)
+void
+unlock(Lock *l)
 {
-	if(_tas(&lk->val))
-		return 0;
-	return 1;
+	if(adec(&l->key) == 0)
+		return;	/* changed from 1 -> 0: no contention */
+	semrelease(&l->sem, 1);
 }
 
-void
-unlock(Lock *lk)
+int
+canlock(Lock *l)
 {
-	lk->val = 0;
+	if(ainc(&l->key) == 1)
+		return 1;	/* changed from 0 -> 1: success */
+	/* Undo increment (but don't miss wakeup) */
+	if(adec(&l->key) == 0)
+		return 0;	/* changed from 1 -> 0: no contention */
+	semrelease(&l->sem, 1);
+	return 0;
 }
diff --git a/sys/src/libc/port/malloc.acid b/sys/src/libc/port/malloc.acid
index ac3ca3a9e..5e7519ad4 100644
--- a/sys/src/libc/port/malloc.acid
+++ b/sys/src/libc/port/malloc.acid
@@ -122,16 +122,18 @@ Profuser = 1;
 Profkernel = 2;
 Proftime = 3;
 Profsample = 4;
-sizeofLock = 4;
+sizeofLock = 8;
 aggr Lock
 {
-	'D' 0 val;
+	'D' 0 key;
+	'D' 4 sem;
 };
 
 defn
 Lock(addr) {
 	complex Lock addr;
-	print("	val	", addr.val, "\n");
+	print("	key	", addr.key, "\n");
+	print("	sem	", addr.sem, "\n");
 };
 
 sizeofQLp = 12;
@@ -150,13 +152,13 @@ QLp(addr) {
 	print("	state	", addr.state, "\n");
 };
 
-sizeofQLock = 16;
+sizeofQLock = 20;
 aggr QLock
 {
 	Lock 0 lock;
-	'D' 4 locked;
-	'A' QLp 8 $head;
-	'A' QLp 12 $tail;
+	'D' 8 locked;
+	'A' QLp 12 $head;
+	'A' QLp 16 $tail;
 };
 
 defn
@@ -170,14 +172,14 @@ QLock(addr) {
 	print("	$tail	", addr.$tail\X, "\n");
 };
 
-sizeofRWLock = 20;
+sizeofRWLock = 24;
 aggr RWLock
 {
 	Lock 0 lock;
-	'D' 4 readers;
-	'D' 8 writer;
-	'A' QLp 12 $head;
-	'A' QLp 16 $tail;
+	'D' 8 readers;
+	'D' 12 writer;
+	'A' QLp 16 $head;
+	'A' QLp 20 $tail;
 };
 
 defn
@@ -438,12 +440,12 @@ Tos(addr) {
 };
 
 complex Tos _tos;
-sizeofPrivate = 12;
+sizeofPrivate = 16;
 aggr Private
 {
 	Lock 0 lk;
-	'D' 4 pid;
-	'D' 8 printfd;
+	'D' 8 pid;
+	'D' 12 printfd;
 };
 
 defn
diff --git a/sys/src/libc/port/mkfile b/sys/src/libc/port/mkfile
index dc2d93694..6d1f1c583 100644
--- a/sys/src/libc/port/mkfile
+++ b/sys/src/libc/port/mkfile
@@ -19,6 +19,7 @@ CFILES=\
 	cleanname.c\
 	crypt.c\
 	ctype.c\
+	cycles.c\
 	encodefmt.c\
 	execl.c\
 	exp.c\
diff --git a/sys/src/libc/port/pool.acid b/sys/src/libc/port/pool.acid
index 2ec6f99af..d4bed5ef7 100644
--- a/sys/src/libc/port/pool.acid
+++ b/sys/src/libc/port/pool.acid
@@ -122,16 +122,18 @@ Profuser = 1;
 Profkernel = 2;
 Proftime = 3;
 Profsample = 4;
-sizeofLock = 4;
+sizeofLock = 8;
 aggr Lock
 {
-	'D' 0 val;
+	'D' 0 key;
+	'D' 4 sem;
 };
 
 defn
 Lock(addr) {
 	complex Lock addr;
-	print("	val	", addr.val, "\n");
+	print("	key	", addr.key, "\n");
+	print("	sem	", addr.sem, "\n");
 };
 
 sizeofQLp = 12;
@@ -150,13 +152,13 @@ QLp(addr) {
 	print("	state	", addr.state, "\n");
 };
 
-sizeofQLock = 16;
+sizeofQLock = 20;
 aggr QLock
 {
 	Lock 0 lock;
-	'D' 4 locked;
-	'A' QLp 8 $head;
-	'A' QLp 12 $tail;
+	'D' 8 locked;
+	'A' QLp 12 $head;
+	'A' QLp 16 $tail;
 };
 
 defn
@@ -170,14 +172,14 @@ QLock(addr) {
 	print("	$tail	", addr.$tail\X, "\n");
 };
 
-sizeofRWLock = 20;
+sizeofRWLock = 24;
 aggr RWLock
 {
 	Lock 0 lock;
-	'D' 4 readers;
-	'D' 8 writer;
-	'A' QLp 12 $head;
-	'A' QLp 16 $tail;
+	'D' 8 readers;
+	'D' 12 writer;
+	'A' QLp 16 $head;
+	'A' QLp 20 $tail;
 };
 
 defn
@@ -504,34 +506,20 @@ MINBLOCKSIZE = 32;
 complex Free checklist:t;
 complex Free checklist:q;
 complex Free checktree:t;
-complex Free ltreewalk:t;
-complex Free ltreewalk:f;
-complex Free treeinsert:tree;
-complex Free treeinsert:node;
-complex Free treeinsert:loc;
-complex Free treeinsert:repl;
-complex Free treedelete:tree;
-complex Free treedelete:node;
-complex Free treedelete:loc;
-complex Free treedelete:lsucc;
-complex Free treedelete:succ;
 complex Free treelookupgt:t;
 complex Free treelookupgt:lastgood;
-complex Free listadd:list;
-complex Free listadd:node;
-complex Free listdelete:list;
-complex Free listdelete:node;
+complex Free treesplay:t;
+complex Free treesplay:N;
+complex Free treesplay:l;
+complex Free treesplay:r;
+complex Free treesplay:y;
 complex Pool pooladd:p;
 complex Alloc pooladd:anode;
-complex Free pooladd:lst;
-complex Free pooladd:olst;
 complex Free pooladd:node;
-complex Free pooladd:parent;
+complex Free pooladd:root;
 complex Pool pooldel:p;
 complex Free pooldel:node;
-complex Free pooldel:lst;
-complex Free pooldel:olst;
-complex Free pooldel:parent;
+complex Free pooldel:root;
 complex Pool dsize2bsize:p;
 complex Pool bsize2asize:p;
 complex Pool blockmerge:pool;