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    SubjectRe: [PATCH] driver core: Add branch prediction hints in really_probe()
    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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