Date: Tue, 21 Jan 2020 21:10:58 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 234733] Setting CPU frequency with sysctl dev.cpu.0.fr slows a Ryzen 2700X down Message-ID: <bug-234733-227-FAtuu9IPPj@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-234733-227@https.bugs.freebsd.org/bugzilla/> References: <bug-234733-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234733 --- Comment #3 from Conrad Meyer <cem@freebsd.org> --- I tried the following test: $ cpuset -l 0 time sha1 <~200MBfile> (burn one result for caching, then repeat 3 trials) I got average 0.24 real, 0.22 user. You might pick a slightly larger file = for bigger and more obvious differences at different steppings. Then I set CPBDis: cpucontrol -m '0xc0010015|=3D0x02000000' /dev/cpuctl0 and repeated the tests; I got average 0.29 real, 0.26 user. I ran "cpucontrol -m '0xc0010015&=3D~0x02000000' /dev/cpuctl0" and got 0.24= /0.22 again. I also tried sysctl dev.cpu.0.freq=3D3400 (on my system, dev.cpu.0.freq_lev= els: 3400/3825 2800/2765 2200/1952). cpucontrol -m '0xc0010015' did not show CPBDis. Also, SHA1 timings remained ~0.24/0.22. I tried dev.cpu.0.freq=3D2800, waited a few seconds, and restored dev.cpu.0.freq=3D3400. cpucontrol -m '0xc0010015' still did not show CPBDis. SHA1 timings seemed = to show the expected boosted performance. My CPU is a Zen1 Threadripper 1950x; perhaps this behavior is different on = Zen+ (Ryzen 2xxx), or there is some difference due to BIOSes. But you might be interested in running the same tests and seeing what you find. --=20 You are receiving this mail because: You are the assignee for the bug.=
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