[src/trunk]: src/sys/uvm switch the UVMHIST counters from mutexes to atomic ops

[chs <chs%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/924f6a360872
branches:  trunk
changeset: 756118:924f6a360872
user:      chs <chs%NetBSD.org@localhost>
date:      Wed Jul 07 01:08:51 2010 +0000

description:
switch the UVMHIST counters from mutexes to atomic ops
to avoid a bad interaction with DIAGNOSTIC.

diffstat:

 sys/uvm/uvm_stat.h |  29 +++++++++++------------------
 1 files changed, 11 insertions(+), 18 deletions(-)

diffs (83 lines):

diff -r 4d7aa58ded94 -r 924f6a360872 sys/uvm/uvm_stat.h
--- a/sys/uvm/uvm_stat.h        Wed Jul 07 00:10:14 2010 +0000
+++ b/sys/uvm/uvm_stat.h        Wed Jul 07 01:08:51 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_stat.h,v 1.46 2010/02/06 12:10:59 uebayasi Exp $   */
+/*     $NetBSD: uvm_stat.h,v 1.47 2010/07/07 01:08:51 chs Exp $        */
 
 /*
  *
@@ -70,11 +70,9 @@
        const char *name;               /* name of this history */
        size_t namelen;                 /* length of name, not including null */
        LIST_ENTRY(uvm_history) list;   /* link on list of all histories */
-       int n;                          /* number of entries */
-       int f;                          /* next free one */
-       int unused;                     /* old location of lock */
+       unsigned int n;                 /* number of entries */
+       unsigned int f;                 /* next free one */
        struct uvm_history_ent *e;      /* the malloc'd entries */
-       kmutex_t l;                     /* lock on this history */
 };
 
 LIST_HEAD(uvm_history_head, uvm_history);
@@ -110,6 +108,7 @@
 #define uvmhist_dump(NAME)
 #else
 #include <sys/kernel.h>                /* for "cold" variable */
+#include <sys/atomic.h>
 
 extern struct uvm_history_head uvm_histories;
 
@@ -121,7 +120,6 @@
        (NAME).namelen = strlen(__STRING(NAME)); \
        (NAME).n = (N); \
        (NAME).f = 0; \
-       mutex_init(&(NAME).l, MUTEX_SPIN, IPL_HIGH); \
        (NAME).e = (struct uvm_history_ent *) \
                malloc(sizeof(struct uvm_history_ent) * (N), M_TEMP, \
                    M_WAITOK); \
@@ -135,7 +133,6 @@
        (NAME).namelen = strlen(__STRING(NAME)); \
        (NAME).n = sizeof(BUF) / sizeof(struct uvm_history_ent); \
        (NAME).f = 0; \
-       mutex_init(&(NAME).l, MUTEX_SPIN, IPL_HIGH); \
        (NAME).e = (struct uvm_history_ent *) (BUF); \
        memset((NAME).e, 0, sizeof(struct uvm_history_ent) * (NAME).n); \
        LIST_INSERT_HEAD(&uvm_histories, &(NAME), list); \
@@ -156,11 +153,11 @@
 
 #define UVMHIST_LOG(NAME,FMT,A,B,C,D) \
 do { \
-       int _i_; \
-       mutex_enter(&(NAME).l); \
-       _i_ = (NAME).f; \
-       (NAME).f = (_i_ + 1 < (NAME).n) ? _i_ + 1 : 0; \
-       mutex_exit(&(NAME).l); \
+       unsigned int _i_, _j_; \
+       do { \
+               _i_ = (NAME).f; \
+               _j_ = (_i_ + 1 < (NAME).n) ? _i_ + 1 : 0; \
+       } while (atomic_cas_uint(&(NAME).f, _i_, _j_) != _i_); \
        if (!cold) \
                microtime(&(NAME).e[_i_].tv); \
        (NAME).e[_i_].cpunum = cpu_number(); \
@@ -178,16 +175,12 @@
 
 #define UVMHIST_CALLED(NAME) \
 do { \
-       { \
-               mutex_enter(&(NAME).l); \
-               _uvmhist_call = _uvmhist_cnt++; \
-               mutex_exit(&(NAME).l); \
-       } \
+       _uvmhist_call = atomic_inc_uint_nv(&_uvmhist_cnt); \
        UVMHIST_LOG(NAME,"called!", 0, 0, 0, 0); \
 } while (/*CONSTCOND*/ 0)
 
 #define UVMHIST_FUNC(FNAME) \
-       static int _uvmhist_cnt = 0; \
+       static unsigned int _uvmhist_cnt = 0; \
        static const char *const _uvmhist_name = FNAME; \
        int _uvmhist_call;