From: "Randy Brukardt" <randy@rrsoftware.com>
Subject: Re: Large number of tasks slows down my program (using debian) - any fix?
Date: Fri, 30 Mar 2018 19:09:49 -0500
Date: 2018-03-30T19:09:49-05:00 [thread overview]
Message-ID: <p9mjke$89b$1@franka.jacob-sparre.dk> (raw)
In-Reply-To: 87h8ox1ect.fsf@nightsong.com
"Paul Rubin" <no.email@nospam.invalid> wrote in message
news:87h8ox1ect.fsf@nightsong.com...
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
...
>> ... Assuming the time quant is 10ms...: 10 x 500 / 4 = 1.25s [+125ms]
>> is the time a task gets back to a core. 1.3s is an eternity.
>
> Sure, if all 500 tasks are cpu-busy then things are in a dreadful state,
> but usually the reason to use so many tasks is concurrent i/o, i.e. most
> of the threads are blocked awaiting input.
If you know what you are doing, surely. Since the OP was experimenting, who
knows?
Assuming that you don't want to wait for your favorite compiler to implement
Ada 2020 (probably a few years yet, we have to figure out what Ada 2020 is
first ;-), my recommendation for parallel execution is to use Brad Moore's
Paraffin libraries. They take care of things like load balancing and
chunking to make good use out of your CPU resources. One can't do that just
by launching one task per iteration for the reasons outlined above.
Randy.
next prev parent reply other threads:[~2018-03-31 0:09 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-28 18:06 Large number of tasks slows down my program (using debian) - any fix? reinert
2018-03-28 18:49 ` Dennis Lee Bieber
2018-03-28 19:06 ` Paul Rubin
2018-03-28 19:21 ` Dmitry A. Kazakov
2018-03-28 20:17 ` reinert
2018-03-29 8:46 ` reinert
2018-03-29 9:18 ` Dmitry A. Kazakov
2018-03-29 15:39 ` Jeffrey R. Carter
2018-04-15 5:20 ` reinert
2018-03-29 22:33 ` Shark8
2018-03-30 9:04 ` Dmitry A. Kazakov
2018-03-30 20:46 ` Paul Rubin
2018-03-31 0:09 ` Randy Brukardt [this message]
2018-03-31 6:00 ` Paul Rubin
2018-03-31 9:37 ` Jacob Sparre Andersen
2018-03-31 10:44 ` Dmitry A. Kazakov
2018-04-02 3:35 ` Randy Brukardt
2018-04-02 6:23 ` alby.gamper
2018-04-02 7:12 ` alby.gamper
2018-04-05 14:07 ` Brad Moore
2018-04-05 15:09 ` Dmitry A. Kazakov
2018-04-07 4:16 ` Brad Moore
2018-04-05 15:30 ` Jeffrey R. Carter
2018-04-05 19:33 ` Spiros Bousbouras
2018-04-05 19:44 ` Simon Wright
2018-04-05 20:25 ` Jeffrey R. Carter
2018-04-06 5:58 ` Benchmarks Game: Thread ring (Was: Large number of tasks slows down my program (using debian) - any fix?) Jacob Sparre Andersen
2018-04-07 4:28 ` Brad Moore
2018-04-06 15:48 ` Large number of tasks slows down my program (using debian) - any fix? Jeffrey R. Carter
2018-04-07 4:39 ` Brad Moore
2018-04-07 8:15 ` Jeffrey R. Carter
2018-04-07 16:28 ` Brad Moore
2018-04-07 18:41 ` Jeffrey R. Carter
2018-04-08 0:29 ` Brad Moore
2018-04-08 8:25 ` Jeffrey R. Carter
2018-04-08 0:06 ` Robert I. Eachus
2018-04-07 16:51 ` Brad Moore
2018-04-07 12:21 ` Simon Wright
2018-04-07 16:57 ` Brad Moore
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