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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1997, 1998, 1999
* Sleepycat Software. All rights reserved.
*/
#include "db_config.h"
#ifndef lint
static const char sccsid[] = "@(#)os_spin.c 11.2 (Sleepycat) 11/3/99";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#if defined(HAVE_PSTAT_GETDYNAMIC)
#include <sys/pstat.h>
#endif
#include <limits.h>
#ifndef _MSC_VER /* _WIN32 */
#include <unistd.h>
#endif
#endif
#include "db_int.h"
#include "os_jump.h"
#if defined(HAVE_PSTAT_GETDYNAMIC)
/*
* __os_pstat_getdynamic --
* HP/UX.
*/
static int
__os_pstat_getdynamic()
{
struct pst_dynamic psd;
return (pstat_getdynamic(&psd,
sizeof(psd), (size_t)1, 0) == -1 ? 1 : psd.psd_proc_cnt);
}
#endif
#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
/*
* CDB___os_sysconf --
* Solaris, Linux.
*/
static int
CDB___os_sysconf()
{
int nproc;
return ((nproc = sysconf(_SC_NPROCESSORS_ONLN)) > 1 ? nproc : 1);
}
#endif
/*
* CDB___os_spin --
* Return the number of default spins before blocking.
*
* PUBLIC: int CDB___os_spin __P((void));
*/
int
CDB___os_spin()
{
/*
* If the application specified a value or we've already figured it
* out, return it.
*
* XXX
* We don't want to repeatedly call the underlying function because
* it can be expensive (e.g., requiring multiple filesystem accesses
* under Debian Linux).
*/
if (DB_GLOBAL(db_tas_spins) != 0)
return (DB_GLOBAL(db_tas_spins));
DB_GLOBAL(db_tas_spins) = 1;
#if defined(HAVE_PSTAT_GETDYNAMIC)
DB_GLOBAL(db_tas_spins) = __os_pstat_getdynamic();
#endif
#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
DB_GLOBAL(db_tas_spins) = CDB___os_sysconf();
#endif
/*
* Spin 50 times per processor, we have anecdotal evidence that this
* is a reasonable value.
*/
if (DB_GLOBAL(db_tas_spins) != 1)
DB_GLOBAL(db_tas_spins) *= 50;
return (DB_GLOBAL(db_tas_spins));
}
/*
* CDB___os_yield --
* Yield the processor.
*
* PUBLIC: void CDB___os_yield __P((u_long));
*/
void
CDB___os_yield(usecs)
u_long usecs;
{
if (CDB___db_jump.j_yield != NULL && CDB___db_jump.j_yield() == 0)
return;
CDB___os_sleep(0, usecs);
}
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