From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,cae92f92d6a1d4b1
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news3.google.com!feeder.news-service.com!85.214.198.2.MISMATCH!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada.Execution_Time
Date: Tue, 28 Dec 2010 22:39:31 +0000
Organization: A noiseless patient Spider
Message-ID: <m2wrmt7c9o.fsf@pushface.org>
References: <ie1ih9$d02$1@news.eternal-september.org>
	<iedfud$ul1$1@news.eternal-september.org>
	<6n1c5myuf2uz$.10jl3ln7il3aq.dlg@40tude.net>
	<8n0mgnFv2sU1@mid.individual.net>
	<1n3o55xjdjr9t.1u33kb75y2jfl$.dlg@40tude.net>
	<8n1142Fto2U1@mid.individual.net>
	<1o5cbm4b1l20d$.19winbma6k5qw.dlg@40tude.net>
	<8n4mskF7mmU1@mid.individual.net>
	<bboyk178uyce.1jx52xgjoblk1$.dlg@40tude.net>
	<8nm30fF7r9U1@mid.individual.net>
	<1akm5muxu9zni.mu91b7pubqw0$.dlg@40tude.net>
	<8nrg25FoucU1@mid.individual.net>
	<2k07hwmh6123.1pgx57welw9of$.dlg@40tude.net>
	<8nsa76Fj4rU1@mid.individual.net>
	<1j9i6trxinqtg$.renlw9wdtpsf.dlg@40tude.net>
	<8nubhsF6e8U1@mid.individual.net>
	<9ulzg911gy1q.hztezq0qtfee$.dlg@40tude.net>
	<C93FC066.36E8%news@findlayw.plus.com>
	<1oq6oggi7rtzj.4u4yyq6m8r74$.dlg@40tude.net>
	<C93FEDF4.36FC%news@findlayw.plus.com>
	<lur4ubobla6x$.1w9ka8t02c6ah.dlg@40tude.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Injection-Info: mx03.eternal-september.org;
 posting-host="dFCm8HWntFqmDIilBLqEJQ";
	logging-data="15452"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX190o40xV7o+adMA1kkasm+5RAxhdaSuSTQ="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (darwin)
Cancel-Lock: sha1:cawztXe0Z8Jy2hi80O+zW7fa8gA=
	sha1:fJ+BGOQz8AGrGWo3AvAjoyIPEoQ=
Xref: g2news2.google.com comp.lang.ada:17181
Date: 2010-12-28T22:39:31+00:00
List-Id: <comp.lang.ada>

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> Yes, the TSC can be read any time, and, if I correctly remember, each
> reading will give a new value. PPC RT clock is also reliable.
>
> There could be certain issues for multi-core processors, you should
> take care that the task synchronizing the counter with UTC would not
> jump from core to core. Alternatively you should synchronize clocks of
> individual cores.

Using the TSC on a MacBook Pro gives very unreliable results (I rather
think the core you're using goes to sleep and you may or may not wake
up using the same core!). However, the system clock (Ada.Calendar) is
precise to a microsecond.