Glauber Costa Messages: 916 Registered: October 2011
Senior Member
On 08/15/2012 05:22 PM, Mel Gorman wrote:
>> I believe it
>> > to be a better and less complicated approach then letting a page appear
>> > and then charging it. Besides being consistent with the rest of memcg,
>> > it won't create unnecessary disturbance in the page allocator
>> > when the allocation is to fail.
>> >
> I still don't get why you did not just return a mem_cgroup instead of a
> handle.
>
Forgot this one, sorry:
The reason is to keep the semantics simple.
What should we return if the code is not compiled in? If we return NULL
for failure, the test becomes
memcg = memcg_kmem_charge_page(gfp, order);
if (!memcg)
exit;
If we're not compiled in, we'd either return positive garbage or we need
to wrap it inside an ifdef
I personally believe to be a lot more clear to standardize on true
to mean "allocation can proceed".
the compiled out case becomes:
if (!true)
exit;
which is easily compiled away altogether. Now of course, using struct
mem_cgroup makes sense, and I have already changed that here.
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