Yosry Ahmed <yosryahmed@xxxxxxxxxx> writes: > On Tue, Nov 7, 2023 at 11:49 PM Vlastimil Babka <vbabka@xxxxxxx> wrote: >> >> On 11/8/23 02:28, Sergey Senozhatsky wrote: >> > On (23/11/07 15:08), Ankur Arora wrote: >> > [..] >> >> +++ b/mm/zsmalloc.c >> >> @@ -2029,7 +2029,6 @@ static unsigned long __zs_compact(struct zs_pool *pool, >> >> dst_zspage = NULL; >> >> >> >> spin_unlock(&pool->lock); >> >> - cond_resched(); >> >> spin_lock(&pool->lock); >> >> } >> >> } >> > >> > I'd personally prefer to have a comment explaining why we do that >> > spin_unlock/spin_lock sequence, which may look confusing to people. >> >> Wonder if it would make sense to have a lock operation that does the >> unlock/lock as a self-documenting thing, and maybe could also be optimized >> to first check if there's a actually a need for it (because TIF_NEED_RESCHED >> or lock is contended). > > +1, I was going to suggest this as well. It can be extended to other > locking types that disable preemption as well like RCU. Something like > spin_lock_relax() or something. Good point. We actually do have exactly that: cond_resched_lock(). (And similar RW lock variants.) >> > Maybe would make sense to put a nice comment in all similar cases. >> > For instance: >> > >> > rcu_read_unlock(); >> > - cond_resched(); >> > rcu_read_lock(); And we have this construct as well: cond_resched_rcu(). I can switch to the alternatives when I send out the next version of the series. Thanks -- ankur
