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An SMP-specific change: Remove unnecessary lock acquires and releases

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surrounding critical sections that consist of (1) a single read or
(2) a single locked RMW operation.

(Thanks to thomma@slip.net (Tamiji Homma) for helping to test
these changes.)
This commit is contained in:
alc 1999-06-30 03:39:29 +00:00
parent 911cea71d3
commit f707f44c0f
1 changed files with 12 additions and 27 deletions
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39
sys/i386/isa/ipl_funcs.c
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@ -23,7 +23,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: ipl_funcs.c,v 1.19 1999/05/09 23:29:56 peter Exp $
* $Id: ipl_funcs.c,v 1.20 1999/05/09 23:40:29 peter Exp $
*/
#include <sys/types.h>
@ -35,28 +35,26 @@
/*
* The volatile bitmap variables must be set atomically. This normally
* involves using a machine-dependent bit-set or `or' instruction.
*
* Note: setbits uses a locked or, making simple cases MP safe.
*/
#ifndef SMP
#define DO_SETBITS(name, var, bits) \
void name(void) \
{ \
setbits(var, bits); \
}
#ifndef SMP
DO_SETBITS(setdelayed, &ipending, loadandclear(&idelayed))
#else /* !SMP */
#define DO_SETBITS(name, var, bits) \
void name(void) \
{ \
IFCPL_LOCK(); \
setbits(var, bits); \
IFCPL_UNLOCK(); \
void setdelayed(void)
{
IFCPL_LOCK();
setbits(&ipending, loadandclear(&idelayed));
IFCPL_UNLOCK();
}
#endif /* !SMP */
DO_SETBITS(setdelayed, &ipending, loadandclear(&idelayed))
DO_SETBITS(setsoftast, &ipending, SWI_AST_PENDING)
DO_SETBITS(setsoftcamnet,&ipending, SWI_CAMNET_PENDING)
DO_SETBITS(setsoftcambio,&ipending, SWI_CAMBIO_PENDING)
@ -71,14 +69,14 @@ DO_SETBITS(schedsoftnet, &idelayed, SWI_NET_PENDING)
DO_SETBITS(schedsofttty, &idelayed, SWI_TTY_PENDING)
DO_SETBITS(schedsoftvm, &idelayed, SWI_VM_PENDING)
#ifndef SMP
unsigned
softclockpending(void)
{
return (ipending & SWI_CLOCK_PENDING);
}
#ifndef SMP
#define GENSPL(name, set_cpl) \
unsigned name(void) \
{ \
@ -144,19 +142,6 @@ splq(intrmask_t mask)
#endif /* SPL_DEBUG_POSTCODE */
unsigned
softclockpending(void)
{
unsigned x;
IFCPL_LOCK();
x = ipending & SWI_CLOCK_PENDING;
IFCPL_UNLOCK();
return (x);
}
/*
* This version has to check for bsp_apic_ready,
* as calling simple_lock() (ie ss_lock) before then deadlocks the system.