svn commit: r332901 - in head/sys: cddl/dev/dtmalloc kern

[Mateusz Guzik]

Author: mjg
Date: Tue Apr 24 01:06:20 2018
New Revision: 332901
URL: https://svnweb.freebsd.org/changeset/base/332901

Log:
  dtrace: depessimize dtmalloc when dtrace is active
  
  Each malloc/free was testing dtrace_malloc_enabled and forcing
  extra reads from the malloc type struct to see if perhaps a
  dtmalloc probe was on.
  
  Treat it like lockstat and sdt: have a global bolean.

Modified:
  head/sys/cddl/dev/dtmalloc/dtmalloc.c
  head/sys/kern/kern_malloc.c

Modified: head/sys/cddl/dev/dtmalloc/dtmalloc.c
==============================================================================
--- head/sys/cddl/dev/dtmalloc/dtmalloc.c       Tue Apr 24 01:04:10 2018        
(r332900)
+++ head/sys/cddl/dev/dtmalloc/dtmalloc.c       Tue Apr 24 01:06:20 2018        
(r332901)
@@ -36,6 +36,9 @@
 #include <sys/dtrace.h>
 #include <sys/dtrace_bsd.h>
 
+extern bool dtrace_malloc_enabled;
+static uint32_t dtrace_malloc_enabled_count;
+
 static d_open_t        dtmalloc_open;
 static int     dtmalloc_unload(void);
 static void    dtmalloc_getargdesc(void *, dtrace_id_t, void *, 
dtrace_argdesc_t *);
@@ -152,6 +155,9 @@ dtmalloc_enable(void *arg, dtrace_id_t id, void *parg)
 {
        uint32_t *p = parg;
        *p = id;
+       dtrace_malloc_enabled_count++;
+       if (dtrace_malloc_enabled_count == 1)
+               dtrace_malloc_enabled = true;
 }
 
 static void
@@ -159,6 +165,9 @@ dtmalloc_disable(void *arg, dtrace_id_t id, void *parg
 {
        uint32_t *p = parg;
        *p = 0;
+       dtrace_malloc_enabled_count--;
+       if (dtrace_malloc_enabled_count == 0)
+               dtrace_malloc_enabled = false;
 }
 
 static void

Modified: head/sys/kern/kern_malloc.c
==============================================================================
--- head/sys/kern/kern_malloc.c Tue Apr 24 01:04:10 2018        (r332900)
+++ head/sys/kern/kern_malloc.c Tue Apr 24 01:06:20 2018        (r332901)
@@ -93,7 +93,8 @@ __FBSDID("$FreeBSD$");
 #ifdef KDTRACE_HOOKS
 #include <sys/dtrace_bsd.h>
 
-dtrace_malloc_probe_func_t     dtrace_malloc_probe;
+bool   __read_frequently                       dtrace_malloc_enabled;
+dtrace_malloc_probe_func_t __read_mostly       dtrace_malloc_probe;
 #endif
 
 #if defined(INVARIANTS) || defined(MALLOC_MAKE_FAILURES) ||            \
@@ -376,7 +377,7 @@ malloc_type_zone_allocated(struct malloc_type *mtp, un
                mtsp->mts_size |= 1 << zindx;
 
 #ifdef KDTRACE_HOOKS
-       if (dtrace_malloc_probe != NULL) {
+       if (__predict_false(dtrace_malloc_enabled)) {
                uint32_t probe_id = mtip->mti_probes[DTMALLOC_PROBE_MALLOC];
                if (probe_id != 0)
                        (dtrace_malloc_probe)(probe_id,
@@ -415,7 +416,7 @@ malloc_type_freed(struct malloc_type *mtp, unsigned lo
        mtsp->mts_numfrees++;
 
 #ifdef KDTRACE_HOOKS
-       if (dtrace_malloc_probe != NULL) {
+       if (__predict_false(dtrace_malloc_enabled)) {
                uint32_t probe_id = mtip->mti_probes[DTMALLOC_PROBE_FREE];
                if (probe_id != 0)
                        (dtrace_malloc_probe)(probe_id,
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"