| Message ID | 0c3fcdaec33bb12b2367860dfab7ed4224ea000c.1635974999.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | aio: Save a few cycles in 'lookup_ioctx()' | expand |
Le 03/11/2021 à 22:31, Christophe JAILLET a écrit : > Use 'percpu_ref_tryget_live_rcu()' instead of 'percpu_ref_tryget_live()' to > save a few cycles when it is known that the rcu lock is already > taken/released. > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> > --- > fs/aio.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/aio.c b/fs/aio.c > index 9c81cf611d65..d189ea13e10a 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -1062,7 +1062,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) > id = array_index_nospec(id, table->nr); > ctx = rcu_dereference(table->table[id]); > if (ctx && ctx->user_id == ctx_id) { > - if (percpu_ref_tryget_live(&ctx->users)) > + if (percpu_ref_tryget_live_rcu(&ctx->users)) > ret = ctx; > } > out: Hi, gentle reminder. Is this patch useful? When I first posted it, percpu_ref_tryget_live_rcu() was really new. Now it is part of linux since 5.16. Saving a few cycles in a function with "lookup" in its name looks always good to me. CJ
Christophe JAILLET <christophe.jaillet@wanadoo.fr> writes: > Le 03/11/2021 à 22:31, Christophe JAILLET a écrit : >> Use 'percpu_ref_tryget_live_rcu()' instead of 'percpu_ref_tryget_live()' to >> save a few cycles when it is known that the rcu lock is already >> taken/released. >> >> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> >> --- >> fs/aio.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/aio.c b/fs/aio.c >> index 9c81cf611d65..d189ea13e10a 100644 >> --- a/fs/aio.c >> +++ b/fs/aio.c >> @@ -1062,7 +1062,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) >> id = array_index_nospec(id, table->nr); >> ctx = rcu_dereference(table->table[id]); >> if (ctx && ctx->user_id == ctx_id) { >> - if (percpu_ref_tryget_live(&ctx->users)) >> + if (percpu_ref_tryget_live_rcu(&ctx->users)) >> ret = ctx; >> } >> out: > > > Hi, > gentle reminder. > > Is this patch useful? > When I first posted it, percpu_ref_tryget_live_rcu() was really new. > Now it is part of linux since 5.16. > > Saving a few cycles in a function with "lookup" in its name looks > always good to me. The patch looks fine to me. Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
diff --git a/fs/aio.c b/fs/aio.c index 9c81cf611d65..d189ea13e10a 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1062,7 +1062,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) id = array_index_nospec(id, table->nr); ctx = rcu_dereference(table->table[id]); if (ctx && ctx->user_id == ctx_id) { - if (percpu_ref_tryget_live(&ctx->users)) + if (percpu_ref_tryget_live_rcu(&ctx->users)) ret = ctx; } out:
Use 'percpu_ref_tryget_live_rcu()' instead of 'percpu_ref_tryget_live()' to save a few cycles when it is known that the rcu lock is already taken/released. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- fs/aio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)