From: Michael Green <mishagreen@gmail.com>
To: Jeff Furlong <jeff.furlong@wdc.com>,
"fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: Re: random_generator=lfsr overhead with more disks?
Date: Fri, 16 Mar 2018 17:16:56 -0400 [thread overview]
Message-ID: <EB5DCCCC-6FFC-4FE5-93FF-4701520AB78A@gmail.com> (raw)
In-Reply-To: <BN3PR0401MB145797FEFD095957854800088FD70@BN3PR0401MB1457.namprd04.prod.outlook.com>
> -How does the cpu utilization look compared between the lfsr and default tausworthe generators? Is the cpu util actually higher on lfsr?
It is actually less when using LFSR with 16 volumes:
Without LFSR (CPU utilization is 5th column):
[root@sm28 ~]# ps -eLo ppid,pid,pri,psr,pcpu,stat,wchan:14,comm | grep fio
PPID PID PRI PSR %CPU STAT WCHAN COMMAND
2239 24684 19 0 0.7 Sl+ hrtimer_nanosl fio
2239 24684 19 0 0.2 Sl+ futex_wait_que fio
2239 24684 19 3 60.4 Rl+ - fio
2239 24684 19 6 60.5 Sl+ - fio
2239 24684 19 1 61.2 Rl+ - fio
2239 24684 19 23 62.5 Sl+ - fio
2239 24684 19 7 60.6 Rl+ - fio
2239 24684 19 18 61.0 Rl+ - fio
2239 24684 19 16 61.0 Rl+ - fio
2239 24684 19 4 62.0 Rl+ - fio
With LFSR:
[root@sm28 ~]# ps -eLo ppid,pid,pri,psr,pcpu,stat,wchan:14,comm | grep fio
2239 25589 19 20 2.7 Sl+ hrtimer_nanosl fio
2239 25589 19 25 0.3 Sl+ futex_wait_que fio
2239 25589 19 16 80.1 Rl+ - fio
2239 25589 19 22 78.0 Rl+ - fio
2239 25589 19 5 82.6 Rl+ - fio
2239 25589 19 4 78.0 Rl+ - fio
2239 25589 19 18 82.7 Rl+ - fio
2239 25589 19 17 80.7 Sl+ 14051005663345 fio
2239 25589 19 23 76.6 Sl+ - fio
2239 25589 19 0 77.6 Rl+ - fio
But almost the same with 1 volume:
Without LFSR
[root@sm28 ~]# ps -eLo ppid,pid,pri,psr,pcpu,stat,wchan:14,comm | grep fio
2239 27559 19 7 4.0 Sl+ hrtimer_nanosl fio
2239 27559 19 2 0.0 Sl+ futex_wait_que fio
2239 27559 19 18 79.4 Rl+ - fio
2239 27559 19 17 79.0 Rl+ - fio
2239 27559 19 6 78.6 Rl+ - fio
2239 27559 19 5 77.6 Rl+ - fio
2239 27559 19 23 82.6 Rl+ - fio
2239 27559 19 3 77.4 Rl+ - fio
2239 27559 19 4 77.1 Sl+ - fio
2239 27559 19 16 75.9 Rl+ - fio
With LFSR:
[root@sm28 ~]# ps -eLo ppid,pid,pri,psr,pcpu,stat,wchan:14,comm | grep fio
2239 27174 19 20 2.0 Sl+ hrtimer_nanosl fio
2239 27174 19 25 0.0 Sl+ futex_wait_que fio
2239 27174 19 16 80.0 Rl+ - fio
2239 27174 19 6 78.4 Rl+ - fio
2239 27174 19 3 77.5 Rl+ - fio
2239 27174 19 5 76.4 Sl+ - fio
2239 27174 19 19 77.1 Rl+ - fio
2239 27174 19 4 76.4 Rl+ - fio
2239 27174 19 7 77.0 Rl+ - fio
2239 27174 19 1 75.8 Rl+ - fio
> -Does a runtime of 2 minutes collect enough data points to assess the condition? What happens if you extend the runtime?
Yes, it does. Shortening the test to 20 sec or extending to 10 min, doesn’t change a thing.
next prev parent reply other threads:[~2018-03-16 21:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-13 19:23 random_generator=lfsr overhead with more disks? Michael Green
2018-03-16 18:45 ` Jeff Furlong
2018-03-16 21:16 ` Michael Green [this message]
2018-03-16 21:16 ` Michael Green
[not found] ` <BN3PR0401MB145715070B7B9F0C71A902318FD70@BN3PR0401MB1457.namprd04.prod.outlook.com>
[not found] ` <902A0A2A-8708-4A94-A09E-5D3C9BFB48FF@gmail.com>
[not found] ` <SN6PR04MB4064D865EBEB79DE2219218D8FD70@SN6PR04MB4064.namprd04.prod.outlook.com>
2018-03-16 22:32 ` Michael Green
2018-03-17 5:42 ` Sitsofe Wheeler
2018-03-29 7:24 ` Michael Green
2018-03-29 8:56 ` Sitsofe Wheeler
2018-03-21 14:34 ` Jens Axboe
2018-03-29 7:28 ` Michael Green
2018-03-29 8:50 ` Sitsofe Wheeler
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