1452 DTrace buffer autoscaling should be less violent

Reviewed by: Gordon Ross <gwr@nexenta.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Garrett D'Amore <garrett@nexenta.com>

4 files changed, 24 insertions, 52 deletions

diff --git a/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize1.d b/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize1.d
index 396a808116..ca8ad44a62 100644
--- a/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize1.d
+++ b/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize1.d
@@ -24,8 +24,6 @@
  * Use is subject to license terms.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 /*
  * ASSERTION:
  *	Checks that setting "bufresize" to "auto" will cause buffer
@@ -34,14 +32,8 @@
  * SECTION: Buffers and Buffering/Buffer Resizing Policy;
  *	Options and Tunables/bufsize;
  *	Options and Tunables/bufresize
- *
- * NOTES:
- *	We use the undocumented "preallocate" option to make sure dtrace(1M)
- *	has enough space in its heap to allocate a buffer as large as the
- *	kernel's trace buffer.
  */
 
-#pragma D option preallocate=100t
 #pragma D option bufresize=auto
 #pragma D option bufsize=100t
 
diff --git a/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize2.d b/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize2.d
index 50b814b1bf..ddb97c89ec 100644
--- a/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize2.d
+++ b/usr/src/cmd/dtrace/test/tst/common/buffering/tst.resize2.d
@@ -24,8 +24,6 @@
  * Use is subject to license terms.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 /*
  * ASSERTION:
  *	Checks that setting "bufresize" to "auto" will cause buffer
@@ -34,14 +32,8 @@
  * SECTION: Buffers and Buffering/Buffer Resizing Policy;
  *	Options and Tunables/aggsize;
  *	Options and Tunables/bufresize
- *
- * NOTES:
- *	We use the undocumented "preallocate" option to make sure dtrace(1M)
- *	has enough space in its heap to allocate a buffer as large as the
- *	kernel's trace buffer.
  */
 
-#pragma D option preallocate=100t
 #pragma D option bufresize=auto
 #pragma D option aggsize=100t
 
diff --git a/usr/src/lib/libdtrace/common/dt_options.c b/usr/src/lib/libdtrace/common/dt_options.c
index 5353bfae52..426f8cb73c 100644
--- a/usr/src/lib/libdtrace/common/dt_options.c
+++ b/usr/src/lib/libdtrace/common/dt_options.c
@@ -24,8 +24,6 @@
  * Use is subject to license terms.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 #include <sys/resource.h>
 #include <sys/mman.h>
 #include <sys/types.h>
@@ -837,30 +835,6 @@ dt_options_load(dtrace_hdl_t *dtp)
 	return (0);
 }
 
-/*ARGSUSED*/
-static int
-dt_opt_preallocate(dtrace_hdl_t *dtp, const char *arg, uintptr_t option)
-{
-	dtrace_optval_t size;
-	void *p;
-
-	if (arg == NULL || dt_optval_parse(arg, &size) != 0)
-		return (dt_set_errno(dtp, EDT_BADOPTVAL));
-
-	if (size > SIZE_MAX)
-		size = SIZE_MAX;
-
-	if ((p = dt_zalloc(dtp, size)) == NULL) {
-		do {
-			size /= 2;
-		} while ((p = dt_zalloc(dtp, size)) == NULL);
-	}
-
-	dt_free(dtp, p);
-
-	return (0);
-}
-
 typedef struct dt_option {
 	const char *o_name;
 	int (*o_func)(dtrace_hdl_t *, const char *, uintptr_t);
@@ -899,7 +873,6 @@ static const dt_option_t _dtrace_ctoptions[] = {
 	{ "linktype", dt_opt_linktype },
 	{ "nolibs", dt_opt_cflags, DTRACE_C_NOLIBS },
 	{ "pgmax", dt_opt_pgmax },
-	{ "preallocate", dt_opt_preallocate },
 	{ "pspec", dt_opt_cflags, DTRACE_C_PSPEC },
 	{ "stdc", dt_opt_stdc },
 	{ "strip", dt_opt_dflags, DTRACE_D_STRIP },
diff --git a/usr/src/uts/common/dtrace/dtrace.c b/usr/src/uts/common/dtrace/dtrace.c
index 1a0599ca31..b6be08379f 100644
--- a/usr/src/uts/common/dtrace/dtrace.c
+++ b/usr/src/uts/common/dtrace/dtrace.c
@@ -10288,14 +10288,17 @@ 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)
 {
 	cpu_t *cp;
 	dtrace_buffer_t *buf;
+	int allocated = 0, desired = 0;
 
 	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);
@@ -10320,7 +10323,8 @@ 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;
@@ -10331,7 +10335,8 @@ 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);
 
@@ -10345,16 +10350,19 @@ 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;
@@ -10362,6 +10370,8 @@ err:
 		buf->dtb_size = 0;
 	} while ((cp = cp->cpu_next) != cpu_list);
 
+	*factor = desired / (allocated > 0 ? allocated : 1);
+
 	return (ENOMEM);
 }
 
@@ -12260,7 +12270,7 @@ 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;
@@ -12622,7 +12632,7 @@ dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
 {
 	dtrace_optval_t *opt = state->dts_options, size;
 	processorid_t cpu;
-	int flags = 0, rval;
+	int flags = 0, rval, factor, divisor = 1;
 
 	ASSERT(MUTEX_HELD(&dtrace_lock));
 	ASSERT(MUTEX_HELD(&cpu_lock));
@@ -12652,7 +12662,7 @@ 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.
@@ -12670,7 +12680,7 @@ 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;
@@ -12679,6 +12689,9 @@ 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);
@@ -12778,7 +12791,8 @@ 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;
@@ -12789,7 +12803,8 @@ 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;
 		}