1452 DTrace buffer autoscaling should be less violent

illumos/illumos-gate@6fb4854bed54ce82bd8610896b64ddebcd4af706

This fixes the tst.resize1.d and tst.resize2.d DTrace tests, which have
been failing since r261122 since they were causing dtrace(1) to attempt to
allocate and use large amounts of memory, and get killed by the OOM killer
as a result.

MFC after:	1 month

1 files changed, 33 insertions, 15 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c b/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
index f35cf73..e85edd1 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
@@ -10853,17 +10853,20 @@ dtrace_buffer_activate(dtrace_state_t *state)
 
 static int
 dtrace_buffer_alloc(dtrace_buffer_t *bufs, size_t size, int flags,
-    processorid_t cpu)
+    processorid_t cpu, int *factor)
 {
 #if defined(sun)
 	cpu_t *cp;
 #endif
 	dtrace_buffer_t *buf;
+	int allocated = 0, desired = 0;
 
 #if defined(sun)
 	ASSERT(MUTEX_HELD(&cpu_lock));
 	ASSERT(MUTEX_HELD(&dtrace_lock));
 
+	*factor = 1;
+
 	if (size > dtrace_nonroot_maxsize &&
 	    !PRIV_POLICY_CHOICE(CRED(), PRIV_ALL, B_FALSE))
 		return (EFBIG);
@@ -10887,7 +10890,8 @@ dtrace_buffer_alloc(dtrace_buffer_t *bufs, size_t size, int flags,
 
 		ASSERT(buf->dtb_xamot == NULL);
 
-		if ((buf->dtb_tomax = kmem_zalloc(size, KM_NOSLEEP)) == NULL)
+		if ((buf->dtb_tomax = kmem_zalloc(size,
+		    KM_NOSLEEP | KM_NORMALPRI)) == NULL)
 			goto err;
 
 		buf->dtb_size = size;
@@ -10898,7 +10902,8 @@ dtrace_buffer_alloc(dtrace_buffer_t *bufs, size_t size, int flags,
 		if (flags & DTRACEBUF_NOSWITCH)
 			continue;
 
-		if ((buf->dtb_xamot = kmem_zalloc(size, KM_NOSLEEP)) == NULL)
+		if ((buf->dtb_xamot = kmem_zalloc(size,
+		    KM_NOSLEEP | KM_NORMALPRI)) == NULL)
 			goto err;
 	} while ((cp = cp->cpu_next) != cpu_list);
 
@@ -10912,27 +10917,29 @@ err:
 			continue;
 
 		buf = &bufs[cp->cpu_id];
+		desired += 2;
 
 		if (buf->dtb_xamot != NULL) {
 			ASSERT(buf->dtb_tomax != NULL);
 			ASSERT(buf->dtb_size == size);
 			kmem_free(buf->dtb_xamot, size);
+			allocated++;
 		}
 
 		if (buf->dtb_tomax != NULL) {
 			ASSERT(buf->dtb_size == size);
 			kmem_free(buf->dtb_tomax, size);
+			allocated++;
 		}
 
 		buf->dtb_tomax = NULL;
 		buf->dtb_xamot = NULL;
 		buf->dtb_size = 0;
 	} while ((cp = cp->cpu_next) != cpu_list);
-
-	return (ENOMEM);
 #else
 	int i;
 
+	*factor = 1;
 #if defined(__amd64__) || defined(__mips__) || defined(__powerpc__)
 	/*
 	 * FreeBSD isn't good at limiting the amount of memory we
@@ -10940,7 +10947,7 @@ err:
 	 * to do something that might well end in tears at bedtime.
 	 */
 	if (size > physmem * PAGE_SIZE / (128 * (mp_maxid + 1)))
-		return(ENOMEM);
+		return (ENOMEM);
 #endif
 
 	ASSERT(MUTEX_HELD(&dtrace_lock));
@@ -10962,7 +10969,8 @@ err:
 
 		ASSERT(buf->dtb_xamot == NULL);
 
-		if ((buf->dtb_tomax = kmem_zalloc(size, KM_NOSLEEP)) == NULL)
+		if ((buf->dtb_tomax = kmem_zalloc(size,
+		    KM_NOSLEEP | KM_NORMALPRI)) == NULL)
 			goto err;
 
 		buf->dtb_size = size;
@@ -10973,7 +10981,8 @@ err:
 		if (flags & DTRACEBUF_NOSWITCH)
 			continue;
 
-		if ((buf->dtb_xamot = kmem_zalloc(size, KM_NOSLEEP)) == NULL)
+		if ((buf->dtb_xamot = kmem_zalloc(size,
+		    KM_NOSLEEP | KM_NORMALPRI)) == NULL)
 			goto err;
 	}
 
@@ -10989,16 +10998,19 @@ err:
 			continue;
 
 		buf = &bufs[i];
+		desired += 2;
 
 		if (buf->dtb_xamot != NULL) {
 			ASSERT(buf->dtb_tomax != NULL);
 			ASSERT(buf->dtb_size == size);
 			kmem_free(buf->dtb_xamot, size);
+			allocated++;
 		}
 
 		if (buf->dtb_tomax != NULL) {
 			ASSERT(buf->dtb_size == size);
 			kmem_free(buf->dtb_tomax, size);
+			allocated++;
 		}
 
 		buf->dtb_tomax = NULL;
@@ -11006,9 +11018,10 @@ err:
 		buf->dtb_size = 0;
 
 	}
+#endif
+	*factor = desired / (allocated > 0 ? allocated : 1);
 
 	return (ENOMEM);
-#endif
 }
 
 /*
@@ -12961,7 +12974,7 @@ dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
 	if (size < (min = dstate->dtds_chunksize + sizeof (dtrace_dynhash_t)))
 		size = min;
 
-	if ((base = kmem_zalloc(size, KM_NOSLEEP)) == NULL)
+	if ((base = kmem_zalloc(size, KM_NOSLEEP | KM_NORMALPRI)) == NULL)
 		return (ENOMEM);
 
 	dstate->dtds_size = size;
@@ -13413,7 +13426,7 @@ dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
 {
 	dtrace_optval_t *opt = state->dts_options, size;
 	processorid_t cpu = 0;;
-	int flags = 0, rval;
+	int flags = 0, rval, factor, divisor = 1;
 
 	ASSERT(MUTEX_HELD(&dtrace_lock));
 	ASSERT(MUTEX_HELD(&cpu_lock));
@@ -13443,7 +13456,7 @@ dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
 			flags |= DTRACEBUF_INACTIVE;
 	}
 
-	for (size = opt[which]; size >= sizeof (uint64_t); size >>= 1) {
+	for (size = opt[which]; size >= sizeof (uint64_t); size /= divisor) {
 		/*
 		 * The size must be 8-byte aligned.  If the size is not 8-byte
 		 * aligned, drop it down by the difference.
@@ -13461,7 +13474,7 @@ dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
 			return (E2BIG);
 		}
 
-		rval = dtrace_buffer_alloc(buf, size, flags, cpu);
+		rval = dtrace_buffer_alloc(buf, size, flags, cpu, &factor);
 
 		if (rval != ENOMEM) {
 			opt[which] = size;
@@ -13470,6 +13483,9 @@ dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
 
 		if (opt[DTRACEOPT_BUFRESIZE] == DTRACEOPT_BUFRESIZE_MANUAL)
 			return (rval);
+
+		for (divisor = 2; divisor < factor; divisor <<= 1)
+			continue;
 	}
 
 	return (ENOMEM);
@@ -13571,7 +13587,8 @@ dtrace_state_go(dtrace_state_t *state, processorid_t *cpu)
 		goto out;
 	}
 
-	spec = kmem_zalloc(nspec * sizeof (dtrace_speculation_t), KM_NOSLEEP);
+	spec = kmem_zalloc(nspec * sizeof (dtrace_speculation_t),
+	    KM_NOSLEEP | KM_NORMALPRI);
 
 	if (spec == NULL) {
 		rval = ENOMEM;
@@ -13582,7 +13599,8 @@ dtrace_state_go(dtrace_state_t *state, processorid_t *cpu)
 	state->dts_nspeculations = (int)nspec;
 
 	for (i = 0; i < nspec; i++) {
-		if ((buf = kmem_zalloc(bufsize, KM_NOSLEEP)) == NULL) {
+		if ((buf = kmem_zalloc(bufsize,
+		    KM_NOSLEEP | KM_NORMALPRI)) == NULL) {
 			rval = ENOMEM;
 			goto err;
 		}