> Module Name: src
> Committed By: matt
> Date: Fri Jan 22 05:17:32 UTC 2010
>
> Modified Files:
> src/sys/uvm [matt-nb5-mips64]: uvm_pglist.c
>
> Log Message:
> Rework the algorithm to allocate contiguous pages to be much much faster.
> (read the comments if you want to know how it's done).
>
>
> To generate a diff of this commit:
> cvs rdiff -u -r1.42 -r1.42.16.1 src/sys/uvm/uvm_pglist.c
> /*
> * Test both the ending and starting pages to see if they are
> * both free. If the ending and starting pages are same page,
> * we only test one of them. If the pages aren't free, there
> * is no reason to continue this iteration so advance to the
> * next address and try again.
> */
> if (VM_PAGE_IS_FREE(&pgs[end - 1]) == 0
> || end - 1 == tryidx + skip
> || VM_PAGE_IS_FREE(&pgs[tryidx + skip]) == 0) {
> try += roundup(num, align);
> skip = 0;
> continue;
> }
I guess this part can be improved and/or fixed as below.
enami.
/*
* If the last page is not free, skip entire region.
*/
if (VM_PAGE_IS_FREE(&pgs[end - 1]) == 0) {
try += roundup(num, align);
skip = 0;
continue;
}
/*
* If the last page is the only page to check,
* we found enough space.
*/
if (end - 1 == tryidx + skip) {
while (skip-- > 0) {
KDASSERT(VM_PAGE_IS_FREE(&pgs[tryidx + skip]));
}
#ifdef PGALLOC_VERBOSE
printf(": ok\n");
#endif
break;
}
/*
* If the start page is not free, start from next boundary
* to the start page.
*/
if (VM_PAGE_IS_FREE(&pgs[tryidx + skip]) == 0) {
try += roundup(skip + 1, align);
skip = 0;
continue;
}
