Messages in this thread Patch in this message | | | Date | Sun, 30 Jul 2006 23:54:03 +0900 (JST) | Subject | Re: [PATCH] simplify update_times (avoid jiffies/jiffies_64 aliasing problem) | From | Atsushi Nemoto <> |
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Let me restart this discussion after about 5 months interval.
On Sun, 05 Mar 2006 02:15:42 +0900 (JST), Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote: > john> I'm not opposed to queuing it up as it seems like a logical > john> cleanup. I'd be fine with it going in before my patch, however > john> it still needs to address i386 lost tick compensation. I worry > john> that addressing that issue before my patchset (which makes the > john> lost tick compensation unnecessary) might be a bit more > john> complex. I think it would be easier going in after my patch. I > john> do think the barrier fix (with a comment) is a good short term > john> fix. > > john> Atsushi: Your thoughts? > > I agree. I missed i386 lost tick case and it seems more complex than > x86_64 case. Your patchset looks to make this cleanup very easy. > Then, here is an updated barrier fix patch.
Now it seems the conversion of the i386 timer code has been finished. We can think this topic again. Here is a patch against current git tree. How about this? And I wonder if there are any point maintaining wall_jiffies now. It seems jiffies and wall_jiffies are always synced.
[PATCH] simplify update_times
In kernel 2.6, update_times() is called directly from timer interrupt, so there is no point calculating ticks here. This also make a barrier added by 5aee405c662ca644980c184774277fc6d0769a84 needless.
Also adjust x86_64 timer interrupt handler with this change.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 7a9b182..298027f 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -423,7 +423,8 @@ #endif if (lost > 0) { handle_lost_ticks(lost, regs); - jiffies += lost; + while (lost--) + do_timer(regs); } /* diff --git a/kernel/timer.c b/kernel/timer.c index 05809c2..3981cae 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1267,12 +1267,9 @@ void run_local_timers(void) */ static inline void update_times(void) { - unsigned long ticks; - - ticks = jiffies - wall_jiffies; - wall_jiffies += ticks; + wall_jiffies++; update_wall_time(); - calc_load(ticks); + calc_load(1); } /* @@ -1284,8 +1281,6 @@ static inline void update_times(void) void do_timer(struct pt_regs *regs) { jiffies_64++; - /* prevent loading jiffies before storing new jiffies_64 value. */ - barrier(); update_times(); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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