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There is no point in vm_contig_launder{,_page}() flushing held pages,

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instead skip over them.  As long as a page is held, it can't be reclaimed by
contigmalloc(M_WAITOK).  Moreover, a held page may be undergoing
modification, e.g., vmapbuf(), so even if the hold were released before the
completion of contigmalloc(), the page might have to be flushed again.

MFC after:	3 weeks
This commit is contained in:
Alan Cox 2010-12-29 20:35:36 +00:00
parent 685a270543
commit fef87167c9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=216807
1 changed files with 4 additions and 5 deletions
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9
sys/vm/vm_contig.c
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@ -100,7 +100,7 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
vm_page_lock_assert(m, MA_OWNED);
object = m->object;
if (!VM_OBJECT_TRYLOCK(object) &&
!vm_pageout_fallback_object_lock(m, next)) {
(!vm_pageout_fallback_object_lock(m, next) || m->hold_count != 0)) {
vm_page_unlock(m);
VM_OBJECT_UNLOCK(object);
return (EAGAIN);
@ -111,7 +111,7 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
return (EBUSY);
}
vm_page_test_dirty(m);
if (m->dirty == 0 && m->hold_count == 0)
if (m->dirty == 0)
pmap_remove_all(m);
if (m->dirty != 0) {
vm_page_unlock(m);
@ -146,8 +146,7 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
return (0);
}
} else {
if (m->hold_count == 0)
vm_page_cache(m);
vm_page_cache(m);
vm_page_unlock(m);
}
VM_OBJECT_UNLOCK(object);
@ -171,7 +170,7 @@ vm_contig_launder(int queue, vm_paddr_t low, vm_paddr_t high)
if (pa < low || pa + PAGE_SIZE > high)
continue;
if (!vm_pageout_page_lock(m, &next)) {
if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) {
vm_page_unlock(m);
continue;
}