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From: Arnd Bergmann <arnd@arndb.de>
To: Martin Peschke <mp3@de.ibm.com>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org, ak@suse.de, hch@infradead.org,
	arjan@infradead.org, James.Smart@emulex.com,
	James.Bottomley@steeleye.com
Subject: Re: [RFC] [Patch 7/8] statistics infrastructure - exploitation prerequisite
Date: Wed, 17 May 2006 01:03:08 +0200	[thread overview]
Message-ID: <200605170103.08917.arnd@arndb.de> (raw)
In-Reply-To: <446A53DE.6060400@de.ibm.com>

Am Wednesday 17 May 2006 00:36 schrieb Martin Peschke:
> Any other hints on how to replace my sched_clock() calls are welcome.
> (I want to measure elapsed times in units that are understandable to
> users without hardware manuals and calculator, such as milliseconds.)

There are a number of APIs that allow you to get the time:

- do_gettimeofday
  potentially slow, reliable TOD clock, microsecond resolution
- ktime_get_ts
  monotonic clock, nanosecond resolution
- getnstimeofday
  reliable, nanosecond TOD clock
- xtime
  jiffie accurate TOD clock, with fast reads
- xtime + wall_to_monotonic
  jiffie accurate monotonic clock, almost as fast
- get_cycles
  highest supported resolution and accuracy, highly
  HW-specific behaviour, may overflow.

	Arnd <><

  reply	other threads:[~2006-05-16 23:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-16 17:47 [RFC] [Patch 7/8] statistics infrastructure - exploitation prerequisite Martin Peschke
2006-05-16 18:28 ` Andrew Morton
2006-05-16 22:36   ` Martin Peschke
2006-05-16 23:03     ` Arnd Bergmann [this message]
2006-05-17  1:23       ` Peter Chubb
2006-05-17  1:27         ` Andi Kleen
2006-05-17  1:43           ` Peter Chubb
2006-05-17  2:24             ` Christoph Lameter
2006-05-17  1:13     ` Peter Chubb
2006-05-17  2:32   ` Nick Piggin

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