Re: [RFC 2/2] x86_64: expand kernel stack to 16K

Rasmus Villemoes
2014-06-03T13:28:28Z

Possibly stupid question: Is it true that any given task can only be
using one wait_queue_t at a time? If so, would it be an idea to put a
wait_queue_t into struct task_struct [maybe union'ed with a struct
wait_bit_queue] and avoid allocating this 40 byte structure repeatedly
on the stack.

E.g., in one of Minchan's stack traces, there are two calls of
mempool_alloc (which itself declares a wait_queue_t) and one
try_to_free_pages (which is the only caller of throttle_direct_reclaim,
which in turn uses wait_event_interruptible_timeout and
wait_event_killable).

Rasmus