svn commit: r250543 - user/attilio/jeff-numa/sys/vm

[John Baldwin]

On 5/13/13 2:59 PM, Attilio Rao wrote:
> On Mon, May 13, 2013 at 8:45 PM, John Baldwin <jhb at freebsd.org> wrote:
>> On 5/13/13 2:23 PM, Attilio Rao wrote:
>>> On Mon, May 13, 2013 at 7:51 PM, John Baldwin <jhb at freebsd.org> wrote:
>>>> On 5/11/13 9:53 PM, Attilio Rao wrote:
>>>>> Author: attilio
>>>>> Date: Sun May 12 01:53:03 2013
>>>>> New Revision: 250543
>>>>> URL: http://svnweb.freebsd.org/changeset/base/250543
>>>>>
>>>>> Log:
>>>>>   Scan all the domains when trying to allocate from freepages.
>>>>>   Some domains may be empty but others may still have some available pages
>>>>>   satisfying the allocations.
>>>>
>>>> It seems like you have nested loops here so you are doing N^2 scans
>>>> rather than N?
>>>
>>> If you want to say so. In most cases N=2 and M=4. However also
>>> consider the less overhead caming from all the adjustement of the
>>> flind because of now split DOMAINS-NFREELISTS concepts.
>>
>> *sigh*
>>
>> No.  Read the code.
> 
> I wrote the code so I certainly read it.
> 
>> vm_phys_alloc_pages() does 'for i = 0; i <
>> vm_ndomains; i++' around calls to vm_phys_alloc_pages_domain() which
>> internally has its _own_ 'for i = 0; i < vm_ndomains; i++'.  Same with
>> vm_phys_alloc_freelist_pages().  You don't need it in both places.
> 
> It is not true.
> vm_phys_alloc_domain_pages() (if this is what you are speaking about)
> doesn't have internally i < vm_ndomains.

Bah, I misread the diff and thought that the change to
vm_phys_alloc_contig() was changing alloc_pages_domain(), my bad.

-- 
John Baldwin