From: Ingo Molnar <mingo@kernel.org>
To: John Stultz <john.stultz@linaro.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Dave Jones <davej@codemonkey.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Richard Cochran <richardcochran@gmail.com>,
Prarit Bhargava <prarit@redhat.com>,
Stephen Boyd <sboyd@codeaurora.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 01/12] clocksource: Simplify clocks_calc_max_nsecs logic
Date: Sat, 7 Mar 2015 10:20:20 +0100 [thread overview]
Message-ID: <20150307092020.GB30888@gmail.com> (raw)
In-Reply-To: <1425696603-16878-2-git-send-email-john.stultz@linaro.org>
* John Stultz <john.stultz@linaro.org> wrote:
> The previous clocks_calc_max_nsecs had some unecessarily
> complex bit logic to find the max interval that could cause
> multiplication overflows. Since this is not in the hot
> path, just do the divide to make it easier to read.
>
> The previous implementation also had a subtle issue
> that it avoided overflows into signed 64bit values, where
So here you write the weird '64bit' form, while in the code you write:
> + * cyc2ns function without overflowing a 64-bit result.
This repeats in later patches as well. I'd suggest using '64-bit'
consistently throughout the whole series.
> as the intervals are always unsigned. This resulted in
> overly conservative intervals, which other saftey margins
> were then added to, reducing the intended interval length.
Typo.
Thanks,
Ingo
next prev parent reply other threads:[~2015-03-07 9:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-07 2:49 [PATCH 00/12] Increased clocksource validation and cleanups (v3) John Stultz
2015-03-07 2:49 ` [PATCH 01/12] clocksource: Simplify clocks_calc_max_nsecs logic John Stultz
2015-03-07 9:20 ` Ingo Molnar [this message]
2015-03-07 2:49 ` [PATCH 02/12] clocksource: Simplify logic around clocksource wrapping saftey margins John Stultz
2015-03-07 9:22 ` Ingo Molnar
2015-03-07 2:49 ` [PATCH 03/12] clocksource: Remove clocksource_max_deferment() John Stultz
2015-03-07 9:18 ` Ingo Molnar
2015-03-07 2:49 ` [PATCH 04/12] clocksource: Add max_cycles to clocksource structure John Stultz
2015-03-07 9:54 ` Ingo Molnar
2015-03-07 2:49 ` [PATCH 05/12] time: Add debugging checks to warn if we see delays John Stultz
2015-03-07 9:22 ` Paul Bolle
2015-03-07 9:29 ` Ingo Molnar
2015-03-07 2:49 ` [PATCH 06/12] time: Add infrastructure to cap clocksource reads to the max_cycles value John Stultz
2015-03-07 9:32 ` Ingo Molnar
2015-03-07 2:49 ` [PATCH 07/12] time: Try to catch clocksource delta underflows John Stultz
2015-03-07 9:34 ` Ingo Molnar
2015-03-07 2:49 ` [PATCH 08/12] time: Add warnings when overflows or underflows are observed John Stultz
2015-03-07 9:40 ` Ingo Molnar
2015-03-09 16:50 ` John Stultz
2015-03-10 5:05 ` Ingo Molnar
2015-03-07 2:50 ` [PATCH 09/12] clocksource: Improve clocksource watchdog reporting John Stultz
2015-03-07 2:50 ` [PATCH 10/12] clocksource: Mostly kill clocksource_register() John Stultz
2015-03-07 9:45 ` Ingo Molnar
2015-03-07 2:50 ` [PATCH 11/12] sparc: Convert to using clocksource_register_hz() John Stultz
2015-03-07 9:46 ` Ingo Molnar
2015-03-07 2:50 ` [PATCH 12/12] clocksource: Add some debug info about clocksources being registered John Stultz
2015-03-07 9:50 ` Ingo Molnar
2015-03-12 3:16 ` John Stultz
-- strict thread matches above, loose matches on Subject: below --
2015-03-12 4:16 [PATCH 00/12] Increased clocksource validation and cleanups (v4) John Stultz
2015-03-12 4:16 ` [PATCH 01/12] clocksource: Simplify clocks_calc_max_nsecs logic John Stultz
2015-01-23 0:09 [PATCH 00/12][RFC] Increased clocksource validation and cleanups (v2) John Stultz
2015-01-23 0:09 ` [PATCH 01/12] clocksource: Simplify clocks_calc_max_nsecs logic John Stultz
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=20150307092020.GB30888@gmail.com \
--to=mingo@kernel.org \
--cc=davej@codemonkey.org.uk \
--cc=john.stultz@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=prarit@redhat.com \
--cc=richardcochran@gmail.com \
--cc=sboyd@codeaurora.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.