From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
To: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Olivier Langlois <olivier@trillion01.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>,
David Miller <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH 09/10] sched: task_sched_runtime introduce micro optimization
Date: Wed, 01 May 2013 14:55:33 -0400 [thread overview]
Message-ID: <51816525.7060305@gmail.com> (raw)
In-Reply-To: <CAPM31RJ0HWQCU=oDnd=iTyEZzsTS3xSe89rmgVK8cd8umAC5BQ@mail.gmail.com>
> Stronger:
>
> +#ifdef CONFIG_64BIT
> + if (!p->on_cpu)
> + return p->se.sum_exec_runtime;
> +#endif
>
> [ Or !p->on_cpu || !add_delta ].
>
> We can take the racy read versus p->on_cpu since:
> If we race with it leaving cpu: we take lock, we're correct
> If we race with it entering cpu: unaccounted time ---> 0, this is
> indistinguishable from the read occurring a few cycles earlier.
OK, agreed. That's nice.
next prev parent reply other threads:[~2013-05-01 18:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-30 3:17 [PATCH v3 0/7] posix-cpu-timers fixlet kosaki.motohiro
2013-04-30 3:17 ` [PATCH 01/10] events: Protect access via task_subsys_state_check() kosaki.motohiro
2013-04-30 3:17 ` [PATCH 02/10] vm: add no-mmu vm_iomap_memory() stub kosaki.motohiro
2013-04-30 3:17 ` [PATCH 03/10] ARM: OMAP4: hwmod data: make 'ocp2scp_usb_phy_phy_48m" as the main clock kosaki.motohiro
2013-04-30 3:17 ` [PATCH 04/10] posix-cpu-timers: don't account cpu timer after stopped thread runtime accounting kosaki.motohiro
2013-04-30 3:38 ` KOSAKI Motohiro
2013-04-30 3:17 ` [PATCH 05/10] posix-cpu-timers: fix acounting delta_exec twice kosaki.motohiro
2013-04-30 3:17 ` [PATCH 06/10] posix-cpu-timers: fix wrong timer initialization kosaki.motohiro
2013-04-30 13:34 ` Olivier Langlois
2013-04-30 3:17 ` [PATCH 07/10] posix-cpu-timers: timer functions must use timer time instead of clock time kosaki.motohiro
2013-04-30 3:17 ` [PATCH 08/10] posix-cpu-timers: check_thread_timers() uses task_sched_runtime() kosaki.motohiro
2013-04-30 3:17 ` [PATCH 09/10] sched: task_sched_runtime introduce micro optimization kosaki.motohiro
2013-05-01 11:00 ` Peter Zijlstra
2013-05-01 11:50 ` Paul Turner
2013-05-01 18:55 ` KOSAKI Motohiro [this message]
2013-05-01 18:42 ` KOSAKI Motohiro
2013-04-30 3:17 ` [PATCH 10/10] posix-cpu-timers: cleanup cpu_{clock,timer}_sample{,_group} kosaki.motohiro
2013-05-01 11:01 ` [PATCH v3 0/7] posix-cpu-timers fixlet Peter Zijlstra
2013-05-01 18:45 ` KOSAKI Motohiro
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