diff options
Diffstat (limited to 'db2/os/os_spin.c')
| -rw-r--r-- | db2/os/os_spin.c | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/db2/os/os_spin.c b/db2/os/os_spin.c index fb693c2..2fd21d0 100644 --- a/db2/os/os_spin.c +++ b/db2/os/os_spin.c @@ -1,14 +1,14 @@ /*- * See the file LICENSE for redistribution information. * - * Copyright (c) 1997 + * Copyright (c) 1997, 1998 * Sleepycat Software. All rights reserved. */ #include "config.h" #ifndef lint -static const char sccsid[] = "@(#)os_spin.c 10.3 (Sleepycat) 11/25/97"; +static const char sccsid[] = "@(#)os_spin.c 10.7 (Sleepycat) 5/20/98"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES @@ -29,28 +29,33 @@ static const char sccsid[] = "@(#)os_spin.c 10.3 (Sleepycat) 11/25/97"; int __os_spin() { - extern int __db_tsl_spins; + static long sys_val; /* If the application specified the spins, use its value. */ - if (__db_tsl_spins != 0) - return (__db_tsl_spins); + if (DB_GLOBAL(db_tsl_spins) != 0) + return (DB_GLOBAL(db_tsl_spins)); + + /* If we've already figured this out, return the value. */ + if (sys_val != 0) + return (sys_val); /* * XXX - * Sysconf: Solaris uses _SC_NPROCESSORS_ONLN to return the number - * of online processors. I don't know if this call is portable or - * not. + * Solaris and Linux use _SC_NPROCESSORS_ONLN to return the number of + * online processors. We don't want to repeatedly call sysconf because + * it's quite expensive (requiring multiple filesystem accesses) under + * Debian Linux. + * + * Spin 50 times per processor -- we have anecdotal evidence that this + * is a reasonable value. */ #if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN) - { - long sys_val; - - sys_val = sysconf(_SC_NPROCESSORS_ONLN); - if (sys_val > 0) - return (sys_val * 50); - } + if ((sys_val = sysconf(_SC_NPROCESSORS_ONLN)) > 1) + sys_val *= 50; + else + sys_val = 1; +#else + sys_val = 1; #endif - - /* Default to a single processor. */ - return (1); + return (sys_val); } |