Jiri Slaby wrote: > On 04/14/2008 04:12 PM, Timur Tabi wrote: >> Unfortunately, the author of the patch, York, is out this week, so I'll have >> to >> take care of this. It'd be easier to modify rh_alloc() so that it doesn't >> sleep, so that's what I'm going to do. > > Anyway, why do you need the spin lock there (and not mutex)?
I don't know. A spinlock just seemed obvious. Why would I prefer a mutex? We need a mutual exclusion device in order to prevent multiple threads from opening the DIU driver simultaneously. When the driver is opened the first time, it needs to initialize the hardware. The hardware can't be initialized unless we allocate a buffer first. Now, we could pre-allocate the buffer, but then this would be a permanent 5MB (8MB if we eliminate rh_alloc) allocation of physically contiguous memory. I'm assuming that this would be a bad thing. It wouldn't eliminate the spinlock, but at least we wouldn't be calling kmalloc(). I open to suggestion for improvements. I'm still going to post the rh_alloc atomic patch, because I think it makes sense anyway. This should fix the sleep-within-spinlock problem, but it does not fix the kmalloc-5MB-in-spinlock problem. -- Timur Tabi Linux kernel developer at Freescale _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
