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Date: Wed, 7 Oct 2009 10:02:27 +0200 (CEST)
From: John Kacur <jkacur@...hat.com>
To: linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
tglx@...utronix.de, john stultz <johnstul@...ibm.com>
cc: Clark Williams <williams@...hat.com>, Ingo Molnar <mingo@...e.hu>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/2] time: remove xtime_cache
@John Stultz
I also backported this patch to 2.6.31.2-rt13, could you please look it
over and see if it looks okay to you?
@Thomas
Same as the previous patch, please consider queuing this for -rt14 and we
can drop it in the future because John Stultz submitted it upstream.
Thanks
>From 868ee3f7346a90ae3b529ac24996f059cc322a82 Mon Sep 17 00:00:00 2001
From: tip-bot for john stultz <johnstul@...ibm.com>
Date: Mon, 5 Oct 2009 11:54:53 +0000
Subject: [PATCH] time: Remove xtime_cache
Commit-ID: 7bc7d637452383d56ba4368d4336b0dde1bb476d
Gitweb: http://git.kernel.org/tip/7bc7d637452383d56ba4368d4336b0dde1bb476d
Author: john stultz <johnstul@...ibm.com>
AuthorDate: Fri, 2 Oct 2009 16:24:15 -0700
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Mon, 5 Oct 2009 13:52:02 +0200
time: Remove xtime_cache
With the prior logarithmic time accumulation patch, xtime will now
always be within one "tick" of the current time, instead of
possibly half a second off.
This removes the need for the xtime_cache value, which always
stored the time at the last interrupt, so this patch cleans that up
removing the xtime_cache related code.
This is a bit simpler, but still could use some wider testing.
Signed-off-by: John Stultz <johnstul@...ibm.com>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: John Kacur <jkacur@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
LKML-Reference: <1254525855.7741.95.camel@...alhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: John Kacur <jkacur@...hat.com>
---
kernel/time.c | 1 -
kernel/time/timekeeping.c | 20 ++------------------
2 files changed, 2 insertions(+), 19 deletions(-)
diff --git a/kernel/time.c b/kernel/time.c
index 35d1aaa..01944b5 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -136,7 +136,6 @@ static inline void warp_clock(void)
write_atomic_seqlock_irq(&xtime_lock);
wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
xtime.tv_sec += sys_tz.tz_minuteswest * 60;
- update_xtime_cache(0);
write_atomic_sequnlock_irq(&xtime_lock);
clock_was_set();
}
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4630874..4a0920d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -48,16 +48,8 @@ static unsigned long total_sleep_time; /* seconds */
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
-static struct timespec xtime_cache __attribute__ ((aligned (16)));
-void update_xtime_cache(u64 nsec)
-{
- xtime_cache = xtime;
- timespec_add_ns(&xtime_cache, nsec);
-}
-
struct clocksource *clock;
-
#ifdef CONFIG_GENERIC_TIME
/**
* clocksource_forward_now - update clock to the current time
@@ -233,7 +225,6 @@ int do_settimeofday(struct timespec *tv)
xtime = *tv;
- update_xtime_cache(0);
clock->error = 0;
ntp_clear();
@@ -435,7 +426,6 @@ void __init timekeeping_init(void)
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
- update_xtime_cache(0);
total_sleep_time = 0;
write_atomic_sequnlock_irqrestore(&xtime_lock, flags);
}
@@ -467,7 +457,6 @@ static int timekeeping_resume(struct sys_device *dev)
wall_to_monotonic.tv_sec -= sleep_length;
total_sleep_time += sleep_length;
}
- update_xtime_cache(0);
/* re-base the last cycle value */
clock->cycle_last = 0;
clock->cycle_last = clocksource_read(clock);
@@ -608,7 +597,6 @@ static void clocksource_adjust(s64 offset)
(NTP_SCALE_SHIFT - clock->shift);
}
-
/**
* logarithmic_accumulation - shifted accumulation of cycles
*
@@ -652,7 +640,6 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
return offset;
}
-
/**
* update_wall_time - Uses the current clocksource to increment the wall time
*
@@ -661,7 +648,6 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
void update_wall_time(void)
{
cycle_t offset;
- u64 nsecs;
int shift = 0, maxshift;
/* Make sure we're fully resumed: */
@@ -725,8 +711,6 @@ void update_wall_time(void)
clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
clock->error += clock->xtime_nsec << (NTP_SCALE_SHIFT - clock->shift);
- update_xtime_cache(cyc2ns(clock, offset));
-
/* check to see if there is a new clocksource to use */
change_clocksource();
update_vsyscall(&xtime, clock);
@@ -761,7 +745,7 @@ void monotonic_to_bootbased(struct timespec *ts)
unsigned long get_seconds(void)
{
- return xtime_cache.tv_sec;
+ return xtime.tv_sec;
}
EXPORT_SYMBOL(get_seconds);
@@ -774,7 +758,7 @@ struct timespec current_kernel_time(void)
do {
seq = read_atomic_seqbegin(&xtime_lock);
- now = xtime_cache;
+ now = xtime;
} while (read_atomic_seqretry(&xtime_lock, seq));
return now;
--
1.6.0.6
--
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