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Optimize pmap_page_index() and fix some comments.

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This commit is contained in:
gwr 1994-11-30 15:45:19 +00:00
parent 3e65533997
commit 8c09a8895b
1 changed files with 46 additions and 30 deletions
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76
sys/arch/sun3/sun3/pmap.c
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@ -1,4 +1,4 @@
/* $NetBSD: pmap.c,v 1.39 1994/11/28 19:17:09 gwr Exp $ */
/* $NetBSD: pmap.c,v 1.40 1994/11/30 15:45:19 gwr Exp $ */
/*
* Copyright (c) 1994 Gordon W. Ross
@ -94,14 +94,17 @@
#endif
/*
* globals shared between here and sun3_startup
* XXX - Look at relationship twix pmap and ^
* Globals shared between here and sun3_startup:
* For simplicity, this interface retains the variables
* that were used in the old interface (without NONCONTIG).
* These are set in pmap_bootstrap() and used
* in pmap_next_page().
*/
/* Kernel virtual address space available: */
extern vm_offset_t virtual_avail, virtual_end;
/* Physical address space available: */
extern vm_offset_t avail_start, avail_end;
/* used to skip the Sun3/50 video RAM */
/* The "hole" (used to skip the Sun3/50 video RAM) */
extern vm_offset_t hole_start, hole_size;
/* statistics... */
@ -110,7 +113,7 @@ struct pmap_stats {
int ps_enter_secondpv; /* pv nonheads entered */
int ps_unlink_pvfirst; /* of pv_unlinks on head */
int ps_unlink_pvsearch; /* of pv_unlink searches */
int ps_pmeg_faultin; /* pmegs reloaded */
int ps_pmeg_faultin; /* pmegs reloaded */
int ps_changeprots; /* of calls to changeprot */
int ps_changewire; /* useless wiring changes */
int ps_npg_prot_all; /* of active pages protected */
@ -684,7 +687,13 @@ pmeg_allocate(pmap, va)
if (!pmegp) {
panic("pmeg_allocate: failed");
}
/* This will put it on the free list. */
/*
* Remove mappings to free-up a pmeg
* (so it will go onto the free list).
* XXX - Should this call up into the VM layer
* to notify it when pages are deactivated?
* See: vm_page.c:vm_page_deactivate(vm_page_t)
*/
pmap_remove_range(pmegp->pmeg_owner,
pmegp->pmeg_va,
pmegp->pmeg_va + NBSG);
@ -1474,16 +1483,19 @@ pmap_virtual_space(v_start, v_end)
}
/*
* How many physical pages will pmap_next_page() return?
* One may return a number larger that the actual number of
* free pages if that is convenient (i.e. physical memory
* might have some small holes not worth counting here).
* The return value is used to allocate per-page arrays.
* Return the number of page indices in the range of
* possible return values for pmap_page_index() for
* all addresses provided by pmap_next_page(). This
* return value is used to allocate per-page data.
*
* Note that a machine with a "hole" in physical memory
* may include the pages in the hole in this count, and
* skip the pages in the hole in pmap_next_page().
*/
u_int
pmap_free_pages()
{
int i, bytes;
int bytes;
bytes = avail_end - avail_start;
return(sun3_btop(bytes));
@ -1491,38 +1503,42 @@ pmap_free_pages()
/*
* If there are still physical pages available, put the address of
* the next available one at paddr and return non-zero, otherwise
* return zero to indicate that there are no more free pages.
* the next available one at paddr and return TRUE. Otherwise,
* return FALSE to indicate that there are no more free pages.
* Note that avail_next is set to avail_start in pmap_bootstrap().
*
* Imporant: The page indices of the pages returned here must be
* in ascending order.
*/
int
pmap_next_page(paddr)
vm_offset_t *paddr;
{
/* Used up all ranges? */
if (avail_next >= avail_end)
return FALSE;
/* Have memory, will return TRUE */
*paddr = avail_next;
avail_next += NBPG;
/* Is it time to skip over the hole? */
if (avail_next == hole_start)
avail_next += sun3_round_page(hole_size);
/* Any available memory remaining? */
if (avail_next >= avail_end)
return FALSE;
/* Have memory, will travel... */
*paddr = avail_next;
avail_next += NBPG;
return TRUE;
}
/*
* pmap_page_index()
*
* Given a physical address, return the page number that it is in
* the block of free memory. Return -1 if not in managed range.
* Given a physical address, return a page index.
*
* There can be some values that we never return (i.e. a hole)
* as long as the pages in the hole were not given to the VM code
* by pmap_next_page() and our return values are less than the
* value that was returned by pmap_free_pages().
* There can be some values that we never return (i.e. a hole)
* as long as the range of indices returned by this function
* is smaller than the value returned by pmap_free_pages().
* The returned index does NOT need to start at zero.
*
* XXX - Should make this a macro in pmap.h
*/
u_long
pmap_page_index(pa)
@ -1531,9 +1547,9 @@ pmap_page_index(pa)
u_long idx;
if (pa < avail_start || pa >= avail_end)
return -1;
panic("pmap_page_index");
return (sun3_btop(pa - avail_start));
return (sun3_btop(pa));
}