Messages in this thread | | | Date | Thu, 15 Dec 2011 17:22:53 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH] usb: fix number of mapped SG DMA entries |
| |
On 12/15/2011 05:01 PM, Alan Stern wrote:
>> Is there anything special you do to get into this kind of situation? >> Like 16GiB of memory on 32bit with highmem and a brutal disk/io test >> case so? > > As I understand it, the typical case is that two SG entries in a row > refer to adjacent pages of physical memory. The mapping routine then > collapses them into a single entry referring to all the pages. > > However, this is not the sort of thing you can deliberately cause, > unless you set up your SG list by hand.
Thanks, both of you for the explanation.
> > Alan Stern
Sebastian
| |