Messages in this thread | | | Date | Thu, 18 Dec 2008 13:48:03 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] ring_bufer: fix BUF_PAGE_SIZE |
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* Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
> > impact: make BUF_PAGE_SIZE changeable. > > Except allocating/freeing page and the code using PAGE_MASK, > all code expect buffer_page's length is BUF_PAGE_SIZE. > > This patch make this behavior more concordant. > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 668bbb5..0cf6caf 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -158,6 +158,10 @@ struct buffer_page { > void *page; /* Actual data page */ > }; > > +#define BUF_PAGE_ORDER 0 > +#define BUF_PAGE_SIZE (PAGE_SIZE << BUF_PAGE_ORDER) > +#define BUF_PAGE_MASK (~(BUF_PAGE_SIZE - 1)) > + > /* > * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing > * this issue out. > @@ -165,7 +169,7 @@ struct buffer_page { > static inline void free_buffer_page(struct buffer_page *bpage) > { > if (bpage->page) > - free_page((unsigned long)bpage->page); > + free_pages((unsigned long)bpage->page, BUF_PAGE_ORDER);
hm, why? Non-order-0 allocations are pretty evil - why would we ever want to do them?
Ingo
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