Messages in this thread | | | Date | Wed, 6 Jun 2007 02:35:39 +0530 | From | "Satyam Sharma" <> | Subject | Re: [PATCH] S390: Replace calls to __get_free_pages() with __get_dma_pages(). |
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Hi,
On 6/6/07, Robert P. J. Day <rpjday@mindspring.com> wrote: > > Replace a number of calls to __get_free_pages() with the corresponding > calls to __get_dma_pages(). > [...] > once the __GFP_DMA argument is removed, it does look weird to see > the first argument of just 0. should that be filled in with > GFP_ATOMIC as christopher lameter suggested?
Yes, I suppose so ... GFP_ATOMIC can dip into the emergency pools so would also make this code a bit more "robust" than using "0" (== GFP_NOWAIT) and it's not that GFP_ATOMIC "waits" on anything either ...
> - (void *)__get_free_pages(__GFP_DMA, > + (void *)__get_dma_pages(0,
GFP_NOWAIT == 0, so the macro GFP_NOWAIT is the one to use if you really don't want any change in behaviour (and as the comment above GFP_NOWAIT says, it's much better to use that name than simply specify "0").
Off-topic, but I wonder what are the valid usage cases / scenarios for GFP_NOWAIT? The obvious answer is somebody might want to be a way-too-polite citizen and stay off the emergency pools even from atomic context, but why would anybody want to do /that/ ... [ BTW there are 3 users of GFP_NOWAIT in kernel code, but there could be more that simply specify "0" to get same behaviour. ]
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