From: Peter Zijlstra <peterz@infradead.org>
To: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, Christoph Hellwig <hch@lst.org>,
keescook@chromium.org, John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 07/25] hrtimer: Reduce conditional code (hres_active)
Date: Mon, 25 Sep 2017 15:55:42 +0200 [thread overview]
Message-ID: <20170925135542.sc4czjbb2j3s5jsj@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20170831105826.120809106@linutronix.de>
On Thu, Aug 31, 2017 at 12:23:36PM -0000, Anna-Maria Gleixner wrote:
> The hrtimer_cpu_base struct has the CONFIG_HIGH_RES_TIMERS conditional
> struct member hres_active. All related functions to this member are
> conditional as well.
>
> There is no functional change, when the hres_active member is unconditional
> with all related functions and is set to zero during initialization. This
> makes the code easier to read.
But you make what was a compile time dead-code-elimination into a
runtime load-and-branch.
Unless the compiler is overly clever and is able to deduce from the lack
of assignments that it must always be 0, is it?
next prev parent reply other threads:[~2017-09-25 13:55 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-31 12:23 [PATCH 00/25] hrtimer: Provide softirq context hrtimers Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 01/25] hrtimer: Use predefined function for updating next_timer Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 02/25] hrtimer: Correct blantanly wrong comment Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 03/25] hrtimer: Fix kerneldoc for struct hrtimer_cpu_base Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 04/25] hrtimer: Cleanup clock argument in schedule_hrtimeout_range_clock() Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 05/25] hrtimer: Switch for loop to _ffs() evaluation Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 07/25] hrtimer: Reduce conditional code (hres_active) Anna-Maria Gleixner
2017-09-25 13:55 ` Peter Zijlstra [this message]
2017-09-25 14:28 ` Thomas Gleixner
2017-08-31 12:23 ` [PATCH 06/25] hrtimer: Store running timer in hrtimer_clock_base Anna-Maria Gleixner
2017-09-25 14:44 ` Peter Zijlstra
2017-09-28 12:45 ` Thomas Gleixner
2017-08-31 12:23 ` [PATCH 08/25] hrtimer: Reduce conditional code (expires_next, next_timer) Anna-Maria Gleixner
2017-09-26 12:10 ` Peter Zijlstra
2017-09-28 8:07 ` Thomas Gleixner
2017-08-31 12:23 ` [PATCH 09/25] hrtimer: Reduce conditional code (hrtimer_reprogram()) Anna-Maria Gleixner
2017-09-26 12:07 ` Peter Zijlstra
2017-08-31 12:23 ` [PATCH 10/25] hrtimer: Make handling of hrtimer reprogramming and enqueuing not conditional Anna-Maria Gleixner
2017-09-26 12:14 ` Peter Zijlstra
2017-09-28 8:09 ` Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 11/25] hrtimer: Allow remote hrtimer enqueue with "expires_next" as expiry time Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 13/25] hrtimer: Split out code from hrtimer_start_range_ns() for reuse Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 12/25] hrtimer: Simplify hrtimer_reprogram() call Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 14/25] hrtimer: Split out code from __hrtimer_get_next_event() for reuse Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 15/25] hrtimer: Add clock bases for soft irq context Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 16/25] hrtimer: Allow function reuse for softirq based hrtimer Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 18/25] hrtimer: Enable soft and hard hrtimer Anna-Maria Gleixner
2017-09-26 12:52 ` Peter Zijlstra
2017-09-27 14:18 ` Anna-Maria Gleixner
2017-09-27 15:54 ` Thomas Gleixner
2017-09-27 16:47 ` Peter Zijlstra
2017-08-31 12:23 ` [PATCH 17/25] hrtimer: Implementation of softirq hrtimer handling Anna-Maria Gleixner
2017-09-26 12:40 ` Peter Zijlstra
2017-09-26 15:03 ` Peter Zijlstra
2017-09-27 14:22 ` Anna-Maria Gleixner
2017-09-27 16:46 ` Peter Zijlstra
2017-09-27 16:40 ` Peter Zijlstra
2017-09-28 7:59 ` Thomas Gleixner
2017-09-28 8:15 ` Peter Zijlstra
2017-12-19 8:58 ` Sebastian Andrzej Siewior
2017-12-19 13:21 ` Peter Zijlstra
2017-12-20 8:44 ` Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 20/25] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer Anna-Maria Gleixner
2017-08-31 12:23 ` Anna-Maria Gleixner
2017-09-05 7:03 ` Johannes Berg
2017-09-05 8:49 ` Thomas Gleixner
2017-09-05 8:51 ` Johannes Berg
2017-08-31 12:23 ` [PATCH 19/25] can/bcm: Replace hrtimer_tasklet with softirq based hrtimer Anna-Maria Gleixner
2017-09-01 15:49 ` Oliver Hartkopp
2017-09-01 15:56 ` Thomas Gleixner
2017-09-01 17:02 ` Oliver Hartkopp
2017-09-02 17:56 ` Oliver Hartkopp
2017-08-31 12:23 ` [PATCH 21/25] xfrm: Replace hrtimer tasklet with softirq hrtimer Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 23/25] ALSA/dummy: Replace " Anna-Maria Gleixner
2017-08-31 14:21 ` Takashi Sakamoto
2017-08-31 14:21 ` Takashi Sakamoto
2017-08-31 14:26 ` Takashi Iwai
2017-08-31 14:26 ` Takashi Iwai
2017-08-31 15:36 ` Takashi Iwai
2017-08-31 15:36 ` Takashi Iwai
2017-09-01 10:25 ` Takashi Sakamoto
2017-09-01 10:25 ` Takashi Sakamoto
2017-09-01 11:58 ` Takashi Iwai
2017-09-01 11:58 ` Takashi Iwai
2017-09-02 1:19 ` Takashi Sakamoto
2017-09-02 1:19 ` Takashi Sakamoto
2017-09-04 12:45 ` Takashi Sakamoto
2017-09-05 15:53 ` [PATCH 23/25 v2] " Sebastian Andrzej Siewior
2017-09-05 15:53 ` Sebastian Andrzej Siewior
2017-09-05 16:02 ` Takashi Iwai
2017-09-05 16:02 ` Takashi Iwai
2017-09-05 16:05 ` Takashi Sakamoto
2017-09-05 16:18 ` [PATCH 23/25 v3] " Sebastian Andrzej Siewior
2017-09-05 16:18 ` Sebastian Andrzej Siewior
2017-09-06 4:30 ` Takashi Sakamoto
2017-09-06 4:30 ` Takashi Sakamoto
2017-09-08 8:28 ` [alsa-devel] " Takashi Iwai
2017-09-08 8:28 ` Takashi Iwai
2017-08-31 12:23 ` [PATCH 22/25] softirq: Remove tasklet_hrtimer Anna-Maria Gleixner
2017-08-31 12:23 ` [PATCH 25/25] usb/gadget/NCM: Replace tasklet with softirq hrtimer Anna-Maria Gleixner
2017-10-24 9:45 ` Felipe Balbi
2017-08-31 12:23 ` [PATCH 24/25] net/cdc_ncm: " Anna-Maria Gleixner
2017-08-31 13:33 ` Greg Kroah-Hartman
2017-08-31 13:57 ` Bjørn Mork
2017-09-05 15:42 ` [PATCH 24/25 v2] " Sebastian Andrzej Siewior
2017-08-31 12:36 ` [PATCH 00/25] hrtimer: Provide softirq context hrtimers Anna-Maria Gleixner
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