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Modify vm_hold_load_pages() to allocate pages using VM_ALLOC_NOOBJ rather

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than using the kernel object.  This allows the elimination of page queues
locking from vm_hold_free_pages().
This commit is contained in:
Alan Cox 2009-05-29 18:35:51 +00:00
parent 6760b335c6
commit 623469c996
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=193044
1 changed files with 5 additions and 13 deletions
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18
sys/kern/vfs_bio.c
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@ -3796,30 +3796,25 @@ vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
from = round_page(from);
index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
VM_OBJECT_LOCK(kernel_object);
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
tryagain:
/*
* note: must allocate system pages since blocking here
* could intefere with paging I/O, no matter which
* could interfere with paging I/O, no matter which
* process we are.
*/
p = vm_page_alloc(kernel_object,
((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ |
VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
if (!p) {
atomic_add_int(&vm_pageout_deficit,
(to - pg) >> PAGE_SHIFT);
VM_OBJECT_UNLOCK(kernel_object);
VM_WAIT;
VM_OBJECT_LOCK(kernel_object);
goto tryagain;
}
p->valid = VM_PAGE_BITS_ALL;
pmap_qenter(pg, &p, 1);
bp->b_pages[index] = p;
}
VM_OBJECT_UNLOCK(kernel_object);
bp->b_npages = index;
}
@ -3835,7 +3830,6 @@ vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
to = round_page(to);
newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
VM_OBJECT_LOCK(kernel_object);
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
p = bp->b_pages[index];
if (p && (index < bp->b_npages)) {
@ -3847,13 +3841,11 @@ vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
}
bp->b_pages[index] = NULL;
pmap_qremove(pg, 1);
vm_page_lock_queues();
vm_page_unwire(p, 0);
p->wire_count--;
vm_page_free(p);
vm_page_unlock_queues();
atomic_subtract_int(&cnt.v_wire_count, 1);
}
}
VM_OBJECT_UNLOCK(kernel_object);
bp->b_npages = newnpages;
}