linux-kernel - Re: [PATCH] tools/powercap: Implement powercap_set

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Message-ID: <CAO9wTFjyEngVR10ixYj=G8udRBeKaxAQquPCdi0V638t3WqQfA@mail.gmail.com>
Date: Wed, 14 May 2025 06:50:06 +0530
From: Suchit K <suchitkarunakaran@...il.com>
To: Shuah Khan <skhan@...uxfoundation.org>
Cc: trenn@...e.com, shuah@...nel.org, jwyatt@...hat.com, jkacur@...hat.com, 
	linux-pm@...r.kernel.org, linux-kernel-mentees@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tools/powercap: Implement powercap_set_enabled()

Thanks for the suggestion, Shuah. And I did compile the kernel after
making the changes.


On Wed, 14 May 2025 at 03:33, Shuah Khan <skhan@...uxfoundation.org> wrote:
>
> On 5/10/25 12:47, Suchit Karunakaran wrote:
> > The powercap_set_enabled() function previously returned a dummy value
> > and was marked with a TODO comment. This patch implements the function
> > by writing the desired mode (0 or 1) to /sys/class/powercap/intel-rapl/enabled
>
> The short summary should say cpupower: Implement powercap_set_enabled()
> >
> > Signed-off-by: Suchit Karunakaran <suchitkarunakaran@...il.com>
> > ---
> >   tools/power/cpupower/lib/powercap.c | 22 ++++++++++++++++++----
> >   1 file changed, 18 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/power/cpupower/lib/powercap.c b/tools/power/cpupower/lib/powercap.c
> > index 94a0c69e55ef..7947b9809239 100644
> > --- a/tools/power/cpupower/lib/powercap.c
> > +++ b/tools/power/cpupower/lib/powercap.c
> > @@ -70,6 +70,22 @@ static int sysfs_get_enabled(char *path, int *mode)
> >       return ret;
> >   }
> >
> > +static int sysfs_set_enabled(const char *path, int mode)
> > +{
> > +     int fd;
> > +     char buf[2] = { mode ? '1' : '0', '\n' };
> > +     ssize_t ret;
> > +
> > +     fd = open(path, O_WRONLY);
> > +     if (fd == -1)
> > +             return -1;
> > +
> > +     ret = write(fd, buf, sizeof(buf));
> > +     close(fd);
> > +
> > +     return ret == sizeof(buf) ? 0 : -1;
> > +}
> > +
> >   int powercap_get_enabled(int *mode)
> >   {
> >       char path[SYSFS_PATH_MAX] = PATH_TO_POWERCAP "/intel-rapl/enabled";
> > @@ -77,12 +93,10 @@ int powercap_get_enabled(int *mode)
> >       return sysfs_get_enabled(path, mode);
> >   }
> >
> > -/*
> > - * TODO: implement function. Returns dummy 0 for now.
> > - */
> >   int powercap_set_enabled(int mode)
> >   {
> > -     return 0;
> > +     char path[SYSFS_PATH_MAX] = PATH_TO_POWERCAP "/intel-rapl/enabled";
> > +     return sysfs_set_enabled(path, mode);
>
> Did you compile this?
>
> thanks,
> -- Shuah