linux-kernel - [RFC] mod_timer() helper functions?

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Message-ID: <a24804730905160036j2720c557o347cec1513df9c4a@mail.gmail.com>
Date:	Sat, 16 May 2009 00:36:15 -0700
From:	Chris Peterson <cpeterso@...terso.com>
To:	linux-kernel@...r.kernel.org
Cc:	tglx@...utronix.de
Subject: [RFC] mod_timer() helper functions?

Reviewing the kernel's nearly one-thousand calls to mod_timer(), there
are three basic patterns:

 * multi-second timeouts
 * millisecond timeouts
 * +1 jiffie ASAP events

Few mod_timer() calls actually use the function's 'expires' deadline
time without manually calculating 'jiffies + delay'. The following
helper functions could provide a simpler, more descriptive interface
than the low-level mod_timer() function. Also, when scheduling longer
timers, these helper functions could use round_jiffies() to (secretly)
batch timers on whole seconds to reduce power usage.

Any suggestions? Is there enough value to warrant adding helper
function like these as an alternative to mod_timer()?

chris

---
static inline int mod_timer_seconds(struct timer_list *timer, time_t seconds)
{
	return mod_timer(timer, round_jiffies(jiffies + seconds * HZ));
}

static inline int mod_timer_msecs(struct timer_list *timer, unsigned int msecs)
{
	/* TODO? Round jiffies if within some epsilon of a whole second? */
	return mod_timer(timer, jiffies + msecs_to_jiffies(msecs));
}

static inline int mod_timer_yield(struct timer_list *timer)
{
	/* After these messages, we'll be right back. */
	return mod_timer(timer, jiffies + 1);
}
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