Revise the interface between vm_object_madvise() and vm_page_dontneed() so
that pointless calls to pmap_is_modified() can be easily avoided when performing madvise(..., MADV_FREE). Sponsored by: EMC / Isilon Storage Division
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parent
8c7ca16f63
commit
2051980f97
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=251591
@ -1175,28 +1175,8 @@ vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
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}
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if (advise == MADV_WILLNEED) {
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vm_page_activate(m);
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} else if (advise == MADV_DONTNEED) {
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vm_page_dontneed(m);
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} else if (advise == MADV_FREE) {
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/*
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* Mark the page clean. This will allow the page
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* to be freed up by the system. However, such pages
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* are often reused quickly by malloc()/free()
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* so we do not do anything that would cause
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* a page fault if we can help it.
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*
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* Specifically, we do not try to actually free
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* the page now nor do we try to put it in the
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* cache (which would cause a page fault on reuse).
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*
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* But we do make the page is freeable as we
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* can without actually taking the step of unmapping
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* it.
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*/
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pmap_clear_modify(m);
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m->dirty = 0;
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m->act_count = 0;
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vm_page_dontneed(m);
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} else {
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vm_page_advise(m, advise);
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}
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vm_page_unlock(m);
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if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
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@ -93,6 +93,7 @@ __FBSDID("$FreeBSD$");
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#include <sys/kernel.h>
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#include <sys/limits.h>
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#include <sys/malloc.h>
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#include <sys/mman.h>
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#include <sys/msgbuf.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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@ -2238,10 +2239,10 @@ vm_page_cache(vm_page_t m)
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}
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/*
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* vm_page_dontneed
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* vm_page_advise
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*
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* Cache, deactivate, or do nothing as appropriate. This routine
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* is typically used by madvise() MADV_DONTNEED.
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* is used by madvise().
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*
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* Generally speaking we want to move the page into the cache so
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* it gets reused quickly. However, this can result in a silly syndrome
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@ -2261,13 +2262,31 @@ vm_page_cache(vm_page_t m)
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* The object and page must be locked.
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*/
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void
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vm_page_dontneed(vm_page_t m)
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vm_page_advise(vm_page_t m, int advice)
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{
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int dnw;
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int head;
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int dnw, head;
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vm_page_lock_assert(m, MA_OWNED);
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vm_page_assert_locked(m);
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VM_OBJECT_ASSERT_WLOCKED(m->object);
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if (advice == MADV_FREE) {
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/*
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* Mark the page clean. This will allow the page to be freed
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* up by the system. However, such pages are often reused
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* quickly by malloc() so we do not do anything that would
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* cause a page fault if we can help it.
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*
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* Specifically, we do not try to actually free the page now
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* nor do we try to put it in the cache (which would cause a
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* page fault on reuse).
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*
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* But we do make the page is freeable as we can without
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* actually taking the step of unmapping it.
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*/
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pmap_clear_modify(m);
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m->dirty = 0;
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m->act_count = 0;
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} else if (advice != MADV_DONTNEED)
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return;
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dnw = PCPU_GET(dnweight);
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PCPU_INC(dnweight);
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@ -2294,7 +2313,7 @@ vm_page_dontneed(vm_page_t m)
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pmap_clear_reference(m);
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vm_page_aflag_clear(m, PGA_REFERENCED);
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if (m->dirty == 0 && pmap_is_modified(m))
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if (advice != MADV_FREE && m->dirty == 0 && pmap_is_modified(m))
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vm_page_dirty(m);
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if (m->dirty || (dnw & 0x0070) == 0) {
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@ -370,6 +370,7 @@ void vm_page_free_zero(vm_page_t m);
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void vm_page_wakeup(vm_page_t m);
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void vm_page_activate (vm_page_t);
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void vm_page_advise(vm_page_t m, int advice);
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vm_page_t vm_page_alloc (vm_object_t, vm_pindex_t, int);
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vm_page_t vm_page_alloc_contig(vm_object_t object, vm_pindex_t pindex, int req,
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u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
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@ -381,7 +382,6 @@ void vm_page_cache_free(vm_object_t, vm_pindex_t, vm_pindex_t);
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void vm_page_cache_transfer(vm_object_t, vm_pindex_t, vm_object_t);
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int vm_page_try_to_cache (vm_page_t);
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int vm_page_try_to_free (vm_page_t);
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void vm_page_dontneed(vm_page_t);
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void vm_page_deactivate (vm_page_t);
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void vm_page_dequeue(vm_page_t m);
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void vm_page_dequeue_locked(vm_page_t m);
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