Re: [RFC] per thread page reservation patch
From: Paulo Marques
Date: Fri Jan 07 2005 - 14:23:19 EST
Vladimir Saveliev wrote:
[...]
+ if (order == 0) {
+ page = perthread_pages_alloc();
+ if (page != NULL)
+ return page;
+ }
I hope this has not been extensively discussed yet, and I missed the
thread but, does everybody think this is a good thing?
This seems like a very asymmetrical behavior. If the code explicitly
reserves pages, it should explicitly use them, or it will become
impossible to track down who is using what (not to mention that this
will slow down every regular user of __alloc_pages, even if it is just
for a quick test).
Why are there specialized functions to reserve the pages, but then they
are used through the standard __alloc_pages interface?
At the very least this test should be moved to the very beginning of the
function. It is of no use to calculate "can_try_harder" before running
this code if it will use a reserved page.
Having a specialized function to get the reserved pages, would also make
the logic in "perthread_pages_reserve" more clear (i.e., that comment
would become unnecessary), and lose the test to "in_interrupt()" in
"perthread_pages_alloc", if I'm reading this correctly.
--
Paulo Marques - www.grupopie.com
"A journey of a thousand miles begins with a single step."
Lao-tzu, The Way of Lao-tzu
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