| Message ID | d674a102bb9afb07298070f1efd730a94e0fa3bc.1513591276.git.christophe.leroy@c-s.fr |
|---|---|
| State | New |
| Headers | show |
| Series | [1/4] gpio: sysfs: change 'value' attribute to prealloc | expand |
On Mon, Dec 18, 2017 at 11:08 AM, Christophe Leroy <christophe.leroy@c-s.fr> wrote: > A 'perf record' on an app continuously writing in the 'value' > attribute show that most of the time is spent in kstrtol() > > --17.99%--value_store > | > |--10.17%--kstrtoint > | | > | |--8.82%--kstrtoll > | > |--2.50%--gpiod_set_value_cansleep > | > |--1.82%--u16_gpio_set > | > |--1.46%--value_store > > The normal case is to write 0 or 1 in the attribute, therefore > this patch avoids the call to kstrtol() in the most common cases > > Then 'perf record' shows > > --7.21%--value_store > | > |--2.69%--u16_gpio_set > | > |--1.47%--value_store > | > |--1.08%--gpiod_set_value_cansleep > | > |--0.60%--mutex_lock > | > --0.58%--mutex_unlock > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Patch applied. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index bb10e8ed456e..31e2352632a2 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -8,6 +8,7 @@ #include <linux/interrupt.h> #include <linux/kdev_t.h> #include <linux/slab.h> +#include <linux/ctype.h> #include "gpiolib.h" @@ -124,7 +125,7 @@ static ssize_t value_store(struct device *dev, { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; - ssize_t status; + ssize_t status = 0; mutex_lock(&data->mutex); @@ -133,7 +134,11 @@ static ssize_t value_store(struct device *dev, } else { long value; - status = kstrtol(buf, 0, &value); + if (size <= 2 && isdigit(buf[0]) && + (size == 1 || buf[1] == '\n')) + value = buf[0] - '0'; + else + status = kstrtol(buf, 0, &value); if (status == 0) { gpiod_set_value_cansleep(desc, value); status = size;
A 'perf record' on an app continuously writing in the 'value' attribute show that most of the time is spent in kstrtol() --17.99%--value_store | |--10.17%--kstrtoint | | | |--8.82%--kstrtoll | |--2.50%--gpiod_set_value_cansleep | |--1.82%--u16_gpio_set | |--1.46%--value_store The normal case is to write 0 or 1 in the attribute, therefore this patch avoids the call to kstrtol() in the most common cases Then 'perf record' shows --7.21%--value_store | |--2.69%--u16_gpio_set | |--1.47%--value_store | |--1.08%--gpiod_set_value_cansleep | |--0.60%--mutex_lock | --0.58%--mutex_unlock Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- drivers/gpio/gpiolib-sysfs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)