linux.kernel - 26 new messages in 17 topics - digest

linux.kernel
http://groups.google.com/group/linux.kernel?hl=en

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Today's topics:

* timers: Reduce __run_timers() latency for empty list - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/9be12def62cea4b8?hl=en
* x86, kaslr: Clarify RANDOMIZE_BASE_MAX_OFFSET - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/dc9d26f210168c8e?hl=en
* [RFC] netfilter: nf_conntrack: don't relase a conntrack with non-zero refcnt
- 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/1f5bd631cfffab0f?hl=en
* mm/memblock: Add support for excluded memory areas - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/784d76ac5d648f80?hl=en
* iio: mxs-lradc: fix invalid channel number detection - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/90e49850c40f4fca?hl=en
* x86, microcode: Move to a proper location - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/9e4932bfb7c23a46?hl=en
* sys, seccomp: add PR_SECCOMP_EXT and SECCOMP_EXT_ACT_TSYNC - 2 messages, 2
authors
http://groups.google.com/group/linux.kernel/t/e2f632c51e6112a2?hl=en
* Drivers: hv: Implement the file copy service - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/e6745e5c9e6c7e65?hl=en
* linux-next: build failure after merge of the tip tree - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/5d213db28c0ba532?hl=en
* locks: rename locks_remove_flock to locks_remove_file - 9 messages, 1 author
http://groups.google.com/group/linux.kernel/t/eabf2e38520b3a22?hl=en
* cpufreq: cpufreq-cpu0: add dt node parsing for cooling device properties - 1
messages, 1 author
http://groups.google.com/group/linux.kernel/t/96a58763966c5219?hl=en
* pinctrl: Add pinctrl binding for Broadcom Capri SoCs - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/b0e58ba3e23c2b35?hl=en
* qrwlock: Use smp_store_release() in write_unlock() - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/31f786da5ce84591?hl=en
* i2c: i2c-core: fix coding style issues in i2c-core.c - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/0a3fa695b86a6e67?hl=en
* audit: Convert int limit uses to u32 - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/23849f960380d948?hl=en
* mm: thrash detection-based file cache sizing - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/8cc6f8a99500ab70?hl=en
* sysfs_rename_link() and its usage - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/f1f1b010c1a48195?hl=en

==============================================================================
TOPIC: timers: Reduce __run_timers() latency for empty list
http://groups.google.com/group/linux.kernel/t/9be12def62cea4b8?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Jan 14 2014 10:50 am
From: Oleg Nesterov


On 01/13, Paul E. McKenney wrote:
>
> The __run_timers() function currently steps through the list one jiffy at
> a time in order to update the timer wheel. However, if the timer wheel
> is empty, no adjustment is needed other than updating ->timer_jiffies.

Yes, but ->active_timers == 0 doesn't necessarily mean "empty", it only
counts the non-deferrable timers?

> In this case, which is likely to be common for NO_HZ_FULL kernels, the
> kernel currently incurs a large latency for no good reason. This commit
> therefore short-circuits this case.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> kernel/timer.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/kernel/timer.c b/kernel/timer.c
> index 6582b82fa966..21849275828f 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -337,6 +337,17 @@ void set_timer_slack(struct timer_list *timer, int slack_hz)
> }
> EXPORT_SYMBOL_GPL(set_timer_slack);
>
> +static bool catchup_timer_jiffies(struct tvec_base *base)
> +{
> +#ifdef CONFIG_NO_HZ_FULL
> + if (!base->active_timers) {
> + base->timer_jiffies = jiffies;
> + return 1;
> + }
> +