Date: Sat, 19 Nov 2022 10:28:50 +0100 From: Hans Petter Selasky <hps@selasky.org> To: Alexander Leidinger <Alexander@leidinger.net> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: ULE realtime scheduler advice needed Message-ID: <c05bf9ad-e436-9479-bfa0-8305a2ea282a@selasky.org> In-Reply-To: <20221118091828.Horde.xkZUBiYzzOgubFonR22tMzm@webmail.leidinger.net> References: <20221118091828.Horde.xkZUBiYzzOgubFonR22tMzm@webmail.leidinger.net>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi Alexander, Thank you for the pointers. I will try it out. --HPS On 11/18/22 09:18, Alexander Leidinger wrote: > 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. >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?c05bf9ad-e436-9479-bfa0-8305a2ea282a>