From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Large number of tasks slows down my program (using debian) - any fix?
Date: Fri, 30 Mar 2018 11:04:14 +0200
Date: 2018-03-30T11:04:14+02:00 [thread overview]
Message-ID: <p9kuig$lq8$1@gioia.aioe.org> (raw)
In-Reply-To: 9377f941-31d0-4260-818a-8e189aac8c19@googlegroups.com
On 2018-03-30 00:33, Shark8 wrote:
> Hm, you shouldn't be hitting the limit with so few tasks. (500 sounds like a lot, but most OSes you'll be using use an integer-ID; meaning something on the order of 2**32 or 2**64.)
It is a simple calculation. Assuming a context switch were around
1000ns. x 500 tasks / 4 cores = 125ms if all tasks are busy. 125ms is a
long time.
Another factor is scheduling. Assuming the time quant is 10ms (Windows
default) and all task are doing pure calculations uninterrupted by any
I/O, then, again: 10 x 500 / 4 = 1.25s [+125ms] is the time a task gets
back to a core. 1.3s is an eternity.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2018-03-30 9:04 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 [this message]
2018-03-30 20:46 ` Paul Rubin
2018-03-31 0:09 ` Randy Brukardt
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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