lkml.org 
[lkml]   [2010]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [linux-pm] [RFC] PM_QOS api update to use handles 1/5
On Sun 2009-11-29 17:09:53, 640E9920 wrote:
> I'm using this crazy email address because I have problems getting to
> linux.intel.com from home, and my work at intel has changed a bit.
>
> This is the first in a 5 part series that attempts to update PM_QOS to
> use handles instead of named strings in its kernel api. It seams that
> some folks are using pm_qos on hot paths and the overhead of the list
> walks and string compares is a problem.
>
> Most of the changes came from aili@codeaurora.org, and I spent some time
> cleaning up the API.
>
> Also, I couldn't resist myself in renaming the API's a bit give the fact
> that the signatures changed enough that I had to touch all the pm_qos
> users anyway. I changed *requirement* to *request* in keeping with the
> way PM_QOS really only does best effort. I've felt "requirement" is too
> strong a word for the way it works.

Looks good on quick scan. Moving away from strings is certainly good.

> @@ -384,15 +363,14 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
> size_t count, loff_t *f_pos)
> {
> s32 value;
> - int pm_qos_class;
> + struct pm_qos_request_list *pm_qos_req;
>
> - pm_qos_class = (long)filp->private_data;
> if (count != sizeof(s32))
> return -EINVAL;
> if (copy_from_user(&value, buf, sizeof(s32)))
> return -EFAULT;
> - sprintf(name, "process_%d", current->pid);
> - pm_qos_update_requirement(pm_qos_class, name, value);
> + pm_qos_req = (struct pm_qos_request_list *)filp->private_data;
> + pm_qos_update_request(pm_qos_req, value);
>
> return sizeof(s32);
> }

Umm.. passing binary numbers like that... is not exactly good
interface. Think endianness issues when writing to it from high-level
language.

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


\
 
 \ /
  Last update: 2010-01-04 09:35    [from the cache]
©2003-2011 Jasper Spaans