From: Pavel Machek <pavel@ucw.cz>
To: Nigel Cunningham <ncunningham@linuxmail.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
John Stultz <johnstul@us.ibm.com>,
David Shaohua <shaohua.li@intel.com>
Subject: Re: Patch 3/3: Reduce number of get_cmos_time_calls.
Date: Sat, 8 Jan 2005 14:27:18 +0100 [thread overview]
Message-ID: <20050108132718.GD7363@elf.ucw.cz> (raw)
In-Reply-To: <1105177308.5478.43.camel@desktop.cunninghams>
Hi!
> Create new __get_cmos_time patch, which doesn't wait for the start of a
> new second before returning. Adjust timer_suspend to use this as we
> don't appear to need the exact start of a second when suspending.
Basically nice cleanup. I do not know if this does not mean up-to
second error in clock for each suspend/resume?
> --- 913-old/arch/x86_64/kernel/time.c 2004-12-10 14:27:08.000000000 +1100
> +++ 913-new/arch/x86_64/kernel/time.c 2005-01-08 19:39:24.664278320 +1100
> @@ -499,11 +499,56 @@ unsigned long long sched_clock(void)
> return cycles_2_ns(a);
> }
>
> +unsigned long __get_cmos_time(void)
> +{
Missing static?
> +
> + /*
> + * Do we need the spinlock in here too?
> + *
> + * If we're called directly (not via get_cmos_time),
> + * we're in the middle of a sysdev suspend/resume
> + * and interrupts are disabled, so this
> + * should be safe without any locking.
> + * -- NC
> + */
I'd say "Caller is responsible for locking"... and explain this in
caller. Also do not sign comments.
> + do {
> + sec = CMOS_READ(RTC_SECONDS);
> + min = CMOS_READ(RTC_MINUTES);
> + hour = CMOS_READ(RTC_HOURS);
> + day = CMOS_READ(RTC_DAY_OF_MONTH);
> + mon = CMOS_READ(RTC_MONTH);
> + year = CMOS_READ(RTC_YEAR);
> + } while (sec != CMOS_READ(RTC_SECONDS));
> +
> + /*
> + * We know that x86-64 always uses BCD format, no need to check the config
> + * register.
> + */
> +
> + BCD_TO_BIN(sec);
> + BCD_TO_BIN(min);
> + BCD_TO_BIN(hour);
> + BCD_TO_BIN(day);
> + BCD_TO_BIN(mon);
> + BCD_TO_BIN(year);
Whitespace damage?
Pavel
--
People were complaining that M$ turns users into beta-testers...
...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!
prev parent reply other threads:[~2005-01-08 13:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-08 9:42 [RFC] Patches to reduce delay in arch/kernel/time.c Nigel Cunningham
2005-01-08 9:42 ` Patch 1/3: Reduce number of get_cmos_time_calls Nigel Cunningham
2005-01-08 13:21 ` Pavel Machek
2005-01-08 9:42 ` Patch 2/3: " Nigel Cunningham
2005-01-08 13:22 ` Pavel Machek
2005-01-08 9:42 ` Patch 3/3: " Nigel Cunningham
2005-01-08 13:27 ` Pavel Machek [this message]
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