From: "Randy Brukardt" <randy@rrsoftware.com>
Subject: Re: basic question on Ada tasks and running on different cores
Date: Thu, 17 May 2012 23:12:22 -0500
Date: 2012-05-17T23:12:22-05:00 [thread overview]
Message-ID: <jp4i7c$smm$1@munin.nbi.dk> (raw)
In-Reply-To: jp1ivb$o6m$1@adenine.netfront.net
"Jeffrey Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message
news:jp1ivb$o6m$1@adenine.netfront.net...
> On 05/16/2012 05:11 PM, Randy Brukardt wrote:
>>
>> The problem is, if you're trying to implement fine-grained parallelism,
>> you
>> have to surround that code with some sort of scheduling mechanism, and
>> that
>> overhead means you aren't going to get anywhere near 100% of the CPU at
>> any
>> point.
>
> The assumption here is that there are more tasks/threads/parallel things
> than there are processors/cores. That's generally true now, but they way
> things are going, it may not be true in the not-too-distant future (1-atom
> transistors could make for a lot of cores). When you have a core per task
> you no longer need scheduling.
Scheduling includes deciding *what* to run, as well as *when* to run it. If
there are enough cores, *when* becomes trivial, but *what* still requires
overhead (and data communication, as Dmitry noted). There are special cases
were *what* is pre-determined (SIMD machines), but for general workloads,
determining what to run will still add costs.
Randy.
prev parent reply other threads:[~2012-05-18 4:12 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-06 7:38 basic question on Ada tasks and running on different cores Nasser M. Abbasi
2012-05-06 7:59 ` Gautier write-only
2012-05-06 10:02 ` Simon Wright
2012-05-06 10:31 ` Ludovic Brenta
2012-05-06 14:14 ` Robert A Duff
2012-05-06 16:07 ` Vinzent Hoefler
2012-05-06 19:43 ` Ludovic Brenta
[not found] ` <15qdq7df9cji7htp52i9d5f8sqsgmisc3b@invalid.netcom.com>
2012-05-06 21:24 ` Ludovic Brenta
2012-05-06 14:13 ` Robert A Duff
2012-05-07 7:36 ` anon
2012-05-08 7:08 ` Maciej Sobczak
2012-05-08 9:02 ` anon
2012-05-08 9:52 ` Ludovic Brenta
2012-05-09 12:28 ` anon
2012-05-10 2:20 ` Randy Brukardt
2012-05-11 2:38 ` NatarovVI
2012-05-11 8:30 ` Georg Bauhaus
2012-05-16 15:40 ` NatarovVI
2012-05-16 18:03 ` Georg Bauhaus
2012-05-12 0:33 ` Randy Brukardt
2012-05-12 10:57 ` Stephen Leake
2012-05-15 6:55 ` Randy Brukardt
2012-05-15 22:54 ` Shark8
2012-05-16 15:54 ` NatarovVI
2012-05-17 0:11 ` Randy Brukardt
2012-05-17 1:06 ` Jeffrey Carter
2012-05-17 6:50 ` Dmitry A. Kazakov
2012-05-18 4:12 ` Randy Brukardt [this message]
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox