Date: Mon, 29 Dec 2008 09:39:33 -0800 (PST) From: Mikolaj Golub <to.my.trociny@gmail.com> To: "FreeBSD Stable Mailing List" <freebsd-stable@freebsd.org> Subject: Re: can't disable hyperthreading on 7.1 Message-ID: <86y6xylw35.fsf@kopusha.onet> In-Reply-To: <200812241536.10563.0ld@ukr.net> References: <200812241536.10563.0ld@ukr.net>
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On Wed, 24 Dec 2008 15:36:10 +0200 Alexander Melnik wrote: AM> Hi AM> I have several computers with 2 xeon processors with hyperthreading under FreeBSD 7.1-RC2 and in any case can not turn off hyperthreading: AM> [old@vmat ~]$ cat /boot/loader.conf AM> machdep.hyperthreading_allowed="0" AM> machdep.hlt_logical_cpus="1" AM> [old@vmat ~]$ sysctl machdep.hyperthreading_allowed AM> machdep.hyperthreading_allowed: 0 AM> [old@vmat ~]$ sysctl machdep.hlt_logical_cpus AM> machdep.hlt_logical_cpus: 1 AM> [old@vmat ~]$ sysctl hw.ncpu AM> hw.ncpu: 4 AM> If machdep.hyperthreading_allowed = "0", the hw.ncpu must be equal to 2? AM> [old@vmat ~]$ top -nd 1 AM> last pid: 825; load averages: 0.00, 0.00, 0.00 up 0+00:21:19 15:22:24 AM> 17 processes: 1 running, 16 sleeping AM> Mem: 6228K Active, 6984K Inact, 20M Wired, 9520K Buf, 960M Free AM> Swap: 2048M Total, 2048M Free AM> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND AM> 762 root 1 4 0 8428K 3936K sbwait 2 0:00 0.00% sshd AM> 767 old 1 8 0 4396K 2212K wait 2 0:00 0.00% bash AM> 765 old 1 44 0 8428K 3952K select 0 0:00 0.00% sshd AM> 571 root 1 44 0 3184K 1200K select 1 0:00 0.00% syslogd AM> 706 root 1 44 0 5876K 3196K select 0 0:00 0.00% sendmail AM> 716 root 1 8 0 3212K 1276K nanslp 2 0:00 0.00% cron AM> 759 root 1 5 0 3184K 1088K ttyin 2 0:00 0.00% getty AM> 758 root 1 5 0 3184K 1088K ttyin 3 0:00 0.00% getty AM> 760 root 1 5 0 3184K 1088K ttyin 0 0:00 0.00% getty AM> 700 root 1 44 0 5752K 3276K select 0 0:00 0.00% sshd AM> 710 smmsp 1 20 0 5876K 3200K pause 2 0:00 0.00% sendmail AM> 297 root 1 96 0 3128K 1208K select 0 0:00 0.00% dhclient AM> 737 root 1 96 0 3240K 1152K select 3 0:00 0.00% inetd AM> 163 root 1 20 0 1380K 804K pause 0 0:00 0.00% adjkerntz AM> 512 root 1 44 0 1888K 564K select 0 0:00 0.00% devd AM> 313 _dhcp 1 44 0 3128K 1320K select 0 0:00 0.00% dhclient AM> 825 old 1 44 0 3496K 1656K CPU0 0 0:00 0.00% top AM> AM> If machdep.hlt_logical_cpus = "1" in the output top in any case should not be seen processors 2 and 3? You can run vmstat -i | grep cpu to see how many CPUs are actually used. I also observe on some hosts (6.3) with machdep.hlt_logical_cpus=1 that in C column of top output there appear CPU numbers for CPUs that are actually halted according to vmstat -i and I am curious too what this means. -- Mikolaj Golub
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