/* allocate identity-mapped frame */
void *
pagevalloc(void)
{
struct physpage *page;
page = queuepop(&vmshmqueue);
if (page) {
return (void *)page->adr;
}
return NULL;
}
/* allocate buffer entry */
struct bufblk *
bufalloc(void)
{
struct bufblk *blk = NULL;
mtxlk(&buffreelist.lk);
blk = queuepop(&buffreelist.head);
mtxunlk(&buffreelist.lk);
if (!blk) {
blk = bufevict();
}
return blk;
}
long
taskgetid(void)
{
struct taskid *queue = &taskidqueue;
struct taskid *taskid;
long retval = -1;
mtxlk(&queue->lk);
taskid = queuepop(&queue);
if (taskid) {
retval = taskid->id;
}
mtxunlk(&taskid->lk);
return retval;
}
/*
* TODO: evict pages from LRU if none free / low water
*/
struct physpage *
pageallocphys(void)
{
struct physpage *page = NULL;
struct physpage **queue;
long found = 0;
long qid;
long q;
mtxlk(&vmphyslk);
page = queuepop(&vmphysqueue);
mtxunlk(&vmphyslk);
if (!page) {
do {
for (q = 0 ; q < LONGSIZE * CHAR_BIT ; q++) {
mtxlk(&vmlrutab[q].lk);
queue = &vmlrutab[q].list;
page = queuegetlast(queue);
if (page) {
found++;
page->nflt++;
qid = pagecalcqid(page);
if (qid != q) {
mtxlk(&vmlrutab[q].lk);
}
queue = &vmlrutab[qid].list;
queuepush(page, queue);
if (qid != q) {
mtxunlk(&vmlrutab[qid].lk);
}
break;
}
mtxunlk(&vmlrutab[q].lk);
}
if (found) {
break;
}
} while (!found);
}
return page;
}
/* evict buffer; write back to disk */
struct bufblk *
bufevict(void)
{
struct bufblk *blk = NULL;
do {
mtxlk(&buflruqueue.lk);
blk = queuepop(&buflruqueue.head);
mtxunlk(&buflruqueue.lk);
if (!blk) {
/* TODO: wait for queuepop(&buflruqueue.head) */
} else {
if (blk->flg & BUFDIRTY) {
bufwrite(blk);
}
bufclr(blk);
}
} while (!blk);
return blk;
}