On Thu, Mar 10, 2011 at 08:00:32AM -0800, Andi Kleen wrote: > On Tue, Mar 08, 2011 at 07:31:56PM -0500, Stephen Wilson wrote: > > > > Morally, the question of whether an address lies in a gate vma should be asked > > with respect to an mm, not a particular task. > > > > Practically, dropping the dependency on task_struct will help make current and > > future operations on mm's more flexible and convenient. In particular, it > > allows some code paths to avoid the need to hold task_lock. > > > > The only architecture this change impacts in any significant way is x86_64. > > The principle change on that architecture is to mirror TIF_IA32 via > > a new flag in mm_context_t. > > The problem is -- you're adding a likely cache miss on mm_struct for > every 32bit compat syscall now, even if they don't need mm_struct > currently (and a lot of them do not) Unless there's a very good > justification to make up for this performance issue elsewhere > (including numbers) this seems like a bad idea. Hmm I see you're only setting it on exec time actually on rereading the patches. I thought you were changing TS_COMPAT which is in the syscall path. Never mind. I have no problems with doing such a change on exec time. -Andi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>