xnu-792.10.96.tar.gz

[apple/xnu.git] / bsd / vfs / vfs_bio.c

diff --git a/bsd/vfs/vfs_bio.c b/bsd/vfs/vfs_bio.c
index 5371c4b3ab873d7f12cda740063c2dd40118af62..8f6f0633e77d8ff5f9c8fef8f5661590741210ef 100644 (file)
--- a/bsd/vfs/vfs_bio.c
+++ b/bsd/vfs/vfs_bio.c
@@ -215,7 +215,7 @@ buf_timestamp(void)
 int lru_is_stale = LRU_IS_STALE;
 int age_is_stale = AGE_IS_STALE;
 int meta_is_stale = META_IS_STALE;
-
+static int boot_nbuf = 0;
 
 
 /* LIST_INSERT_HEAD() with assertions */
@@ -233,15 +233,19 @@ blistenterhead(struct bufhashhdr * head, buf_t bp)
 static __inline__ void 
 binshash(buf_t bp, struct bufhashhdr *dp)
 {
+#if DIAGNOSTIC
        buf_t   nbp;
+#endif /* DIAGNOSTIC */
 
        BHASHENTCHECK(bp);
 
+#if DIAGNOSTIC
        nbp = dp->lh_first;
        for(; nbp != NULL; nbp = nbp->b_hash.le_next) {
                if(nbp == bp) 
                        panic("buf already in hashlist");
        }
+#endif /* DIAGNOSTIC */
 
        blistenterhead(dp, bp);
 }
@@ -1371,15 +1375,17 @@ bufinit()
        int     metabuf;
        long    whichq;
 
+       nbuf = 0;
        /* Initialize the buffer queues ('freelists') and the hash table */
        for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++)
                TAILQ_INIT(dp);
-       bufhashtbl = hashinit(nbuf, M_CACHE, &bufhash);
+       bufhashtbl = hashinit(nbuf_hashelements, M_CACHE, &bufhash);
 
-       metabuf = nbuf/8; /* reserved for meta buf */
+       metabuf = max_nbuf_headers/8; /* reserved for meta buf */
 
        /* Initialize the buffer headers */
-       for (i = 0; i < nbuf; i++) {
+       for (i = 0; i < max_nbuf_headers; i++) {
+               nbuf++;
                bp = &buf[i];
                bufhdrinit(bp);
 
@@ -1398,24 +1404,24 @@ bufinit()
                binshash(bp, &invalhash);
        }
 
+       boot_nbuf = nbuf;
+
        for (; i < nbuf + niobuf; i++) {
                bp = &buf[i];
                bufhdrinit(bp);
                binsheadfree(bp, &iobufqueue, -1);
        }
 
-        /*
+    /*
         * allocate lock group attribute and group
         */
-        buf_mtx_grp_attr = lck_grp_attr_alloc_init();
-       //lck_grp_attr_setstat(buf_mtx_grp_attr);
+    buf_mtx_grp_attr = lck_grp_attr_alloc_init();
        buf_mtx_grp = lck_grp_alloc_init("buffer cache", buf_mtx_grp_attr);
                
        /*
         * allocate the lock attribute
         */
        buf_mtx_attr = lck_attr_alloc_init();
-       //lck_attr_setdebug(buf_mtx_attr);
 
        /*
         * allocate and initialize mutex's for the buffer and iobuffer pools
@@ -2491,7 +2497,7 @@ allocbuf(buf_t bp, int size)
                                                bp->b_datap = (uintptr_t)zalloc(z);
                                        } else {
                                                bp->b_datap = (uintptr_t)NULL;
-                                               kmem_alloc(kernel_map, (vm_offset_t *)&bp->b_datap, desired_size);
+                                               kmem_alloc_wired(kernel_map, (vm_offset_t *)&bp->b_datap, desired_size);
                                                CLR(bp->b_flags, B_ZALLOC);
                                        }
                                        bcopy((void *)elem, (caddr_t)bp->b_datap, bp->b_bufsize);
@@ -2504,7 +2510,7 @@ allocbuf(buf_t bp, int size)
                                if ((vm_size_t)bp->b_bufsize < desired_size) {
                                        /* reallocate to a bigger size */
                                        bp->b_datap = (uintptr_t)NULL;
-                                       kmem_alloc(kernel_map, (vm_offset_t *)&bp->b_datap, desired_size);
+                                       kmem_alloc_wired(kernel_map, (vm_offset_t *)&bp->b_datap, desired_size);
                                        bcopy((const void *)elem, (caddr_t)bp->b_datap, bp->b_bufsize);
                                        kmem_free(kernel_map, elem, bp->b_bufsize); 
                                } else {
@@ -2519,7 +2525,7 @@ allocbuf(buf_t bp, int size)
                                bp->b_datap = (uintptr_t)zalloc(z);
                                SET(bp->b_flags, B_ZALLOC);
                        } else
-                               kmem_alloc(kernel_map, (vm_offset_t *)&bp->b_datap, desired_size);
+                               kmem_alloc_wired(kernel_map, (vm_offset_t *)&bp->b_datap, desired_size);
                }
        }
        bp->b_bufsize = desired_size;
@@ -2567,6 +2573,16 @@ start:
        if ((*queue > BQUEUES) || (*queue < 0)
                || (*queue == BQ_LAUNDRY) || (*queue == BQ_LOCKED))
                *queue = BQ_EMPTY;
+       /* need to grow number of bufs, add another one rather than recycling */
+       if (nbuf < max_nbuf_headers) {
+               /*
+                * Increment  count now as lock 
+                * is dropped for allocation.
+                * That avoids over commits
+                */
+               nbuf++;
+               goto add_newbufs;
+       }
 
        /*
         * (*queue == BQUEUES) means no preference
@@ -2593,6 +2609,13 @@ start:
                        *queue = BQ_EMPTY;
                        goto found;
                }
+               /*
+                * We have seen is this is hard to trigger.
+                * This is an overcommit of nbufs but needed 
+                * in some scenarios with diskiamges
+                */
+
+add_newbufs:
                lck_mtx_unlock(buf_mtxp);
 
                /* Create a new temporary buffer header */
@@ -2610,6 +2633,9 @@ start:
                        buf_hdr_count++;
                        goto found;
                }
+               /* subtract already accounted bufcount */
+               nbuf--;
+
                bufstats.bufs_sleeps++;
 
                /* wait for a free buffer of any kind */
@@ -2619,7 +2645,6 @@ start:
                /* the hz value is 100; which leads to 10ms */
                ts.tv_nsec = (slptimeo % 1000) * NSEC_PER_USEC * 1000 * 10;
                msleep(&needbuffer, buf_mtxp, slpflag|(PRIBIO+1), (char *)"getnewbuf", &ts);
-
                return (0);
        }
 
@@ -3113,9 +3138,12 @@ count_busy_buffers(void)
        buf_t   bp;
        int     nbusy = 0;
 
-       for (bp = &buf[nbuf]; --bp >= buf; )
+       lck_mtx_lock(buf_mtxp);
+       for (bp = &buf[boot_nbuf]; --bp >= buf; )
                if (!ISSET(bp->b_flags, B_INVAL) && ISSET(bp->b_lflags, BL_BUSY))
                        nbusy++;
+       lck_mtx_unlock(buf_mtxp);
+
        return (nbusy);
 }