Date: Fri, 18 Nov 2022 09:18:28 +0100 From: Alexander Leidinger <Alexander@leidinger.net> To: Hans Petter Selasky <hps@selasky.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: ULE realtime scheduler advice needed Message-ID: <20221118091828.Horde.xkZUBiYzzOgubFonR22tMzm@webmail.leidinger.net> In-Reply-To: <7ad10a5e-29d6-aaef-25cf-407d65f056cc@selasky.org>
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[-- Attachment #1 --] Quoting Hans Petter Selasky <hps@selasky.org> (from Fri, 18 Nov 2022 05:47:58 +0100): > Hi, > > I'm doing some work with audio and have noticed some problems with > the ULE scheduler. I have a program that generate audio based on > key-presses. When no keys are pressed, the load is near 0%, but as > soon as you start pressing keys, the load goes maybe to 80% of a CPU > core. This program I run with rtprio 8 xxx. The issue I observe or > hear actually, is that it takes too long until the scheduler grasps > that this program needs it's own CPU core and stops time-sharing the > program. When I however use cpuset -l xxx rtprio 8 yyy everything is > good, and the program outputs realtime audio in-time. I have something in my mind about ULE not handling idleprio and/or rtprio correctly, but I have no pointer to a validation of this. > Or is this perhaps a CPU frequency stepping issue? You could play with rc.conf (/etc/rc.d/power_profile): performance_cpu_freq="HIGH" performance_cx_lowest="C3" # see sysctl hw.cpu.0 | grep cx economy_cx_lowest="C3" # see sysctl hw.cpu.0 | grep cx Your system may provide other Cx possibilities, and ging to a lower number (e.g. C1) means less power-saving but faster response from the CPU (I do not expect that this is causing the issue you have). > Any advice on where to look? Potential sysctl to play with to change "interactivity detection" in ULE: https://www.mail-archive.com/freebsd-stable@freebsd.org/msg112118.html Bye, Alexander. -- http://www.Leidinger.net Alexander@Leidinger.net: PGP 0x8F31830F9F2772BF http://www.FreeBSD.org netchild@FreeBSD.org : PGP 0x8F31830F9F2772BF [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIzBAABCAAdFiEER9UlYXp1PSd08nWXEg2wmwP42IYFAmN3P9MACgkQEg2wmwP4 2Ib46g/+MHdv1DNmg2mSrSzPDxYx79Vz/HFnMMe1wSGf9DOJll6nheyouIypoE+O rZu+Z9dppbNi+hAMnnSbQ5NHSCj2sI7BR/dOJt0B4f5l0SwmNs6Ph28HXQju12pp /Zmh9AtZZwaw2qCXmbA5uEyEJmkIIsqnXMXQ7HDlPKP+b9q7vj/+XqsO/rE2QCK1 RLYlAGvfdZ2vo/gQovE8k5Bfn+8JtizsNm0Pwj7EZCHNLhgA1vU4QKzjCMWScyhx 0OPxuYiIZcgcKQt3rRBs0ivhodjuEc13BzEiFlQJ8/ILdw7QnWNiWYXxuoKtWC7n T/wKmfqvv7zRwWAQt3fE4BcQZw9Z9fAkLQPX1S/vwprHzlhHZ6mJukUNxgj5FVXG dnQ/+gRHi7av8k2ntWSgkKLn3btb2GMjaQBRmcZ+/R+BHxkI/lJV3oEYRLLRA/Bq SoxURWjJQMBiZcoHsjgCnR62TbPXG1YiJ7YfXMLkgT4pZ19ngIjMSgGALkCS8nGb u00HyIJoccrQvytgIBHgdInUFW6rQdIW9hfzQun7rvVNQ1noqxs9khbFiqUATbZF qDWkPP7sF9cn86p/IFn6xIuo2HaiJXzAviGPKTB+jHnJdd2jOPtNdnAW/pdTKT5l SDm64xoUIaFYqfgV7UsbM+gkdondTeRyC90GYdeOeGEd6ySs4Mg= =lrgw -----END PGP SIGNATURE-----help
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