Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Tue, 6 Nov 2018 15:30:14 +0100 | Subject | Re: [PATCH] driver core: Add branch prediction hints in really_probe() |
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On Tue, Nov 6, 2018 at 2:47 PM Muchun Song <smuchun@gmail.com> wrote: > > If condition is false in most cases. So, add an unlikely() to the if > condition, so that the optimizer assumes that the condition is false. > > Signed-off-by: Muchun Song <smuchun@gmail.com>
Have you measured the practical impact of this patch in any way?
> --- > drivers/base/dd.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 169412ee4ae8..8eba453c4e5d 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -450,7 +450,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) > bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && > !drv->suppress_bind_attrs; > > - if (defer_all_probes) { > + if (unlikely(defer_all_probes)) { > /* > * Value of defer_all_probes can be set only by > * device_defer_all_probes_enable() which, in turn, will call > @@ -508,7 +508,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) > goto probe_failed; > } > > - if (test_remove) { > + if (unlikely(test_remove)) { > test_remove = false; > > if (dev->bus->remove) > -- > 2.17.1 >
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