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Make pmap_extract() lockless. Reviewed by chs@ who reports a ~1% reduction

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in system time during a kernel build on a quad core amd64 system.
This commit is contained in:
ad 2008-06-16 10:31:03 +00:00
parent 94d328c85c
commit 8c49cfa7b6
1 changed files with 46 additions and 23 deletions
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69
sys/arch/x86/x86/pmap.c
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@ -1,4 +1,4 @@
/* $NetBSD: pmap.c,v 1.68 2008/06/06 05:45:16 cegger Exp $ */
/* $NetBSD: pmap.c,v 1.69 2008/06/16 10:31:03 ad Exp $ */
/*
* Copyright (c) 2007 Manuel Bouyer.
@ -154,7 +154,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.68 2008/06/06 05:45:16 cegger Exp $");
__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.69 2008/06/16 10:31:03 ad Exp $");
#include "opt_user_ldt.h"
#include "opt_lockdebug.h"
@ -2817,31 +2817,54 @@ pmap_extract(struct pmap *pmap, vaddr_t va, paddr_t *pap)
pd_entry_t pde;
pd_entry_t * const *pdes;
struct pmap *pmap2;
struct cpu_info *ci;
vaddr_t pa;
lwp_t *l;
bool hard, rv;
kpreempt_disable();
pmap_map_ptes(pmap, &pmap2, &ptes, &pdes);
if (!pmap_pdes_valid(va, pdes, &pde)) {
rv = false;
pa = 0;
l = curlwp;
KPREEMPT_DISABLE(l);
ci = l->l_cpu;
if (__predict_true(!ci->ci_want_pmapload && ci->ci_pmap == pmap) ||
pmap == pmap_kernel()) {
/*
* no need to lock, because it's pmap_kernel() or our
* own pmap and is active. if a user pmap, the caller
* will hold the vm_map write/read locked and so prevent
* entries from disappearing while we are here. ptps
* can disappear via pmap_remove(), pmap_protect() and
* pmap_collect(), but they are called with the vm_map
* write locked.
*/
hard = false;
ptes = PTE_BASE;
pdes = normal_pdes;
} else {
/* we lose, do it the hard way. */
hard = true;
pmap_map_ptes(pmap, &pmap2, &ptes, &pdes);
}
if (pmap_pdes_valid(va, pdes, &pde)) {
pte = ptes[pl1_i(va)];
if (pde & PG_PS) {
pa = (pde & PG_LGFRAME) | (va & (NBPD_L2 - 1));
rv = true;
} else if (__predict_true((pte & PG_V) != 0)) {
pa = pmap_pte2pa(pte) | (va & (NBPD_L1 - 1));
rv = true;
}
}
if (__predict_false(hard)) {
pmap_unmap_ptes(pmap, pmap2);
kpreempt_enable();
return false;
}
pte = ptes[pl1_i(va)];
pmap_unmap_ptes(pmap, pmap2);
kpreempt_enable();
if (pde & PG_PS) {
if (pap != NULL)
*pap = (pde & PG_LGFRAME) | (va & (NBPD_L2 - 1));
return (true);
KPREEMPT_ENABLE(l);
if (pap != NULL) {
*pap = pa;
}
if (__predict_true((pte & PG_V) != 0)) {
if (pap != NULL)
*pap = pmap_pte2pa(pte) | (va & (NBPD_L1 - 1));
return (true);
}
return false;
return rv;
}