Messages in this thread | | | Date | Tue, 22 Aug 2017 22:53:16 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] sched/wait: Break up long wake list walk |
| |
On Tue, Aug 22, 2017 at 01:42:13PM -0700, Linus Torvalds wrote: > +void wait_on_page_bit_or_yield(struct page *page, int bit_nr) > +{ > + if (PageWaiters(page)) { > + yield(); > + return; > + } > + wait_on_page_bit(page, bit_nr); > +}
So _the_ problem with yield() is when you hit this with a RT task it will busy spin and possibly not allow the task that actually has the lock to make progress at all.
So ideally there'd be a timeout or other limit on the amount of yield().
This being bit-spinlocks leaves us very short on state to play with though :/
| |