> On Fri, Nov 15, 2002 at 10:36:18AM -0600, mark tinguely wrote: > > since the allocated space is larger that a physical page (65536 > 4096), > > bus_dmamem_alloc() allocates physical contiguous memory. After repeated > > allocations and frees, the physical memory pages will fragment and the > > allocation will fail. <deleted text>
Chuck Tuffli asks: > When the driver frees the memory with bus_dmamem_free(), can other > drivers or the kernel not use this memory? The memory is avaliable to the kernel/drivers when bus_dmamem_free() is called. The problem for you is that someone else does allocate a page within the 16 page chunk making it unable to reallocatable by you, so the next bus_dmamem_alloc() looks for the next 16 page contiguous chunk. This continues until there is no more 16 page contiguous chunks available and the bus_dmamem_alloc() fails. FreeBSD does not have a physical memory defragmenter. --Mark Tinguely To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
