On 10/11/24 9:49 AM, Breno Leitao wrote: > Whenever an I/O elevator is changed, the system attempts to load a > module for the new elevator. This occurs regardless of whether the > elevator is already loaded or built directly into the kernel. This > behavior introduces unnecessary overhead and potential issues. > > This makes the operation slower, and more error-prone. For instance, > making the problem fixed by [1] visible for users that doesn't even rely > on modules being available through modules. > > Do not try to load the ioscheduler if it is already visible. > > This change brings two main benefits: it improves the performance of > elevator changes, and it reduces the likelihood of errors occurring > during this process. > > [1] Commit e3accac1a976 ("block: Fix elv_iosched_local_module handling of "none" scheduler") > Fixes: 734e1a860312 ("block: Prevent deadlocks when switching elevators") > Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx> > --- > Changelog: > v2: > * Protecet __elevator_find() by elv_list_lock (Christoph Hellwig) > v1: > * https://lore.kernel.org/all/20241010141509.4028059-1-leitao@xxxxxxxxxx/ > > block/elevator.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/block/elevator.c b/block/elevator.c > index 565807f0b1c7..1ac9be3e47d1 100644 > --- a/block/elevator.c > +++ b/block/elevator.c > @@ -106,6 +106,17 @@ static struct elevator_type *__elevator_find(const char *name) > return NULL; > } > > +static struct elevator_type *elevator_find(const char *name) > +{ > + struct elevator_type *e; > + > + spin_lock(&elv_list_lock); > + e = __elevator_find(name); > + spin_unlock(&elv_list_lock); > + > + return e; > +} Probably just drop this helper. If it's only used in one spot, then we don't need to add a helper for it. -- Jens Axboe