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Skip missing page directories in deallocuvm

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Previously, deallocuvm scanned from 0 to KERNBASE in one page
increments, which had a noticable effect on boot time.  Now it skips
over missing page directories.
This commit is contained in:
Austin Clements 2011-09-01 21:29:09 -04:00
parent 1eadf4a8fc
commit 052e18485d
1 changed files with 3 additions and 1 deletions
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4
vm.c
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@ -261,7 +261,9 @@ deallocuvm(pde_t *pgdir, uint oldsz, uint newsz)
a = PGROUNDUP(newsz); a = PGROUNDUP(newsz);
for(; a < oldsz; a += PGSIZE){ for(; a < oldsz; a += PGSIZE){
pte = walkpgdir(pgdir, (char*)a, 0); pte = walkpgdir(pgdir, (char*)a, 0);
if(pte && (*pte & PTE_P) != 0){ if(!pte)
a += (NPTENTRIES - 1) * PGSIZE;
else if((*pte & PTE_P) != 0){
pa = PTE_ADDR(*pte); pa = PTE_ADDR(*pte);
if(pa == 0) if(pa == 0)
panic("kfree"); panic("kfree");