From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: Tony Breeds <tony@bakeyournoodle•com>
Cc: Andrew Morton <akpm@osdl•org>, Daniel Walker <dwalker@mvista•com>,
john stultz <johnstul@us•ibm.com>,
LKML <linux-kernel@vger•kernel.org>,
LinuxPPC-dev <linuxppc-dev@ozlabs•org>,
Thomas Gleixner <tglx@linutronix•de>, Ingo Molnar <mingo@elte•hu>
Subject: Re: [RFC] clocksouce implementation for powerpc
Date: Wed, 20 Jun 2007 20:53:47 +0400 [thread overview]
Message-ID: <46795B9B.2020401@ru.mvista.com> (raw)
In-Reply-To: <20070620065710.GR9768@bakeyournoodle.com>
Hello.
Tony Breeds wrote:
>>>plain text document attachment
>>>(clocksource-add-settimeofday-hook.patch)
>>>From: Tony Breeds <tony@bakeyournoodle•com >
>>>I'm working on a clocksource implementation for all powerpc platforms.
>>>some of these platforms needs to do a little work as part of the
>>>settimeofday() syscall and I can't see a way to do that without adding
>>>this hook to clocksource.
>>I'd like to see how this is used? If the code that uses this API change
>>isn't ready yet, then this patch should really wait..
> This is my current patch to rework arch/powerpc/kernel/time.c to create
> a clocksource. It's not ready for inclusion.
I guess it's been based on the prior work by John Stultz (and me too :-)?
> powerpc needs to keep the vdso in sync whenener settimeodfay() is
> called. Adding the hook the to the clocksource structure was my way of
> allowing this to happen. There are other approaches, but this seemed to
> best allow for runtime. Initially I considered using update_vsyscall()
> but this is called from do_timer(), and I don't need this code run then
> :(
> This has been booted on pSeries and iSeries (I'm using glibc 2.5, which
> uses the vdso gettimeoday())
[...]
> Index: working/arch/powerpc/kernel/time.c
> ===================================================================
> --- working.orig/arch/powerpc/kernel/time.c
> +++ working/arch/powerpc/kernel/time.c
> @@ -74,6 +74,30 @@
> #endif
> #include <asm/smp.h>
>
> +/* powerpc clocksource/clockevent code */
> +
> +/* TODO:
> + * o Code style
> + * * Variable names ... be consistent.
> + *
> + * TODO: Clocksource
> + * o Need a _USE_RTC() clocksource impelementation
> + * o xtime: Either time.c manages it, or clocksource does, not both
If you mean the init. part, this has been already done by me -- I've
implemented read_persistent_clock() and got rid of xtime setting. What's left
is to implemet update_persistent_clock() and get rid of timer_check_rtc()...
> + */
> +
> +#include <linux/clocksource.h>
> +
> +static struct clocksource clocksource_timebase = {
> + .name = "timebase",
> + .rating = 200,
Perhaps we even need to raise the rating to 300 or 400 -- according to
what <linux/clocksource.h> says?
> + .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> + .mask = CLOCKSOURCE_MASK(64),
> + .shift = 22,
PPC64 has issues with the fixed shift value, see:
http://patchwork.ozlabs.org/linuxppc/patch?id=11125
> + .mult = 0, /* To be filled in */
> + .read = NULL, /* To be filled in */
> + .settimeofday = NULL, /* To be filled in */
I don't quite understand why not just init them right away? The values
are fixed anyways.
> +};
> +
> /* keep track of when we need to update the rtc */
> time_t last_rtc_update;
> #ifdef CONFIG_PPC_ISERIES
[...]
> @@ -666,8 +631,8 @@ void timer_interrupt(struct pt_regs * re
> if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) {
> tb_last_jiffy = tb_next_jiffy;
> do_timer(1);
> - timer_recalc_offset(tb_last_jiffy);
> - timer_check_rtc();
> + /* timer_recalc_offset() && timer_check_rtc()
> + * are now called from update_vsyscall() */
I.e. in the softirq context...
[...]
WBR, Sergei
next prev parent reply other threads:[~2007-06-20 16:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070616101126.296384219@inhelltoy.tec.linutronix.de>
[not found] ` <20070616101637.107940593@inhelltoy.tec.linutronix.de>
[not found] ` <1182009083.11539.369.camel@imap.mvista.com>
2007-06-20 6:57 ` [RFC] clocksouce implementation for powerpc Tony Breeds
2007-06-20 14:57 ` Daniel Walker
2007-06-20 17:20 ` Sergei Shtylyov
2007-06-20 17:31 ` Thomas Gleixner
2007-06-20 18:11 ` Sergei Shtylyov
2007-06-22 6:23 ` Tony Breeds
2007-06-20 16:53 ` Sergei Shtylyov [this message]
2007-06-22 6:10 ` Tony Breeds
2007-06-22 12:42 ` Sergei Shtylyov
2007-06-20 21:06 ` john stultz
2007-06-22 6:28 ` Tony Breeds
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=46795B9B.2020401@ru.mvista.com \
--to=sshtylyov@ru$(echo .)mvista.com \
--cc=akpm@osdl$(echo .)org \
--cc=dwalker@mvista$(echo .)com \
--cc=johnstul@us$(echo .)ibm.com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=mingo@elte$(echo .)hu \
--cc=tglx@linutronix$(echo .)de \
--cc=tony@bakeyournoodle$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox