On Jan 22, 2010, at 12:28 AM, enami tsugutomo wrote:
>> 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.
I initially did something like that but realized it didn't really buy me
anything since the compiler will actually do something like that anyways.
