From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Juri Lelli <juri.lelli@gmail.com>,
Clark Williams <williams@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 4/4] tracing: Add __print_ns_to_secs() and __print_ns_without_secs() helpers
Date: Tue, 23 Feb 2016 08:17:57 -0500 [thread overview]
Message-ID: <20160223081757.59f3b698@gandalf.local.home> (raw)
In-Reply-To: <20160223124915.GQ6357@twins.programming.kicks-ass.net>
On Tue, 23 Feb 2016 13:49:15 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, Feb 22, 2016 at 04:26:53PM -0500, Steven Rostedt wrote:
> > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> >
> > To have nanosecond output displayed in a more human readable format, its
> > nicer to convert it to a seconds format (XXX.YYYYYYYYY). The problem is that
> > to do so, the numbers must be divided by NSEC_PER_SEC, and moded too. But as
> > these numbers are 64 bit, this can not be done simply with '/' and '%'
> > operators, but must use do_div() instead.
>
> Would not div_[us]64_rem() make more sense? It would typically result in
> just the one division, instead of two.
The problem is, how do you do that in a printf() statement?
We have "%llu.%09ul" which is two arguments in the printf(). And the
values we are processing can't be modified. Which is why the macro uses
({ }) and creates a temp variable.
-- Steve
next prev parent reply other threads:[~2016-02-23 13:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-22 21:26 [PATCH 0/4] sched: Display deadline bandwidth and other SCHED_DEBUG clean up Steven Rostedt
2016-02-22 21:26 ` [PATCH 1/4] sched: Move sched_feature file setup into debug.c Steven Rostedt
2016-02-29 11:16 ` [tip:sched/core] sched/debug: Move the /sys/kernel/debug/sched_features " tip-bot for Steven Rostedt (Red Hat)
2016-02-22 21:26 ` [PATCH 2/4] sched: Move sched_domain_sysctl to debug.c Steven Rostedt
2016-02-29 11:16 ` [tip:sched/core] sched/debug: " tip-bot for Steven Rostedt (Red Hat)
2016-02-22 21:26 ` [PATCH 3/4] sched: Add bandwidth ratio to /proc/sched_debug Steven Rostedt
2016-02-23 9:55 ` Juri Lelli
2016-02-29 11:16 ` [tip:sched/core] sched/debug: Add deadline scheduler " tip-bot for Steven Rostedt (Red Hat)
2016-02-22 21:26 ` [PATCH 4/4] tracing: Add __print_ns_to_secs() and __print_ns_without_secs() helpers Steven Rostedt
2016-02-23 12:49 ` Peter Zijlstra
2016-02-23 13:17 ` Steven Rostedt [this message]
2016-02-23 14:01 ` Peter Zijlstra
2016-02-23 14:30 ` Steven Rostedt
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