Date: Thu, 14 Sep 2006 09:20:24 -0500 From: Dan Nelson <dnelson@allantgroup.com> To: Ian Smith <smithi@nimnet.asn.au> Cc: questions@freebsd.org, "Tamouh H." <hakmi@rogers.com>, Giorgos Keramidas <keramida@freebsd.org> Subject: Re: Top not showing cpu usage even remotely accurately Message-ID: <20060914142023.GB91336@dan.emsphone.com> In-Reply-To: <Pine.BSF.3.96.1060914165639.8650A-100000@gaia.nimnet.asn.au> References: <20060914054758.GA77575@gothmog.pc> <Pine.BSF.3.96.1060914165639.8650A-100000@gaia.nimnet.asn.au>
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In the last episode (Sep 14), Ian Smith said: > I still can't fathom what top tells me on a UP 5.5-STABLE system (300MHz > Celeron if speed's relevant). I initiated this thread (weeks ago :) re > seeing 0.0% idle (as expected) during buildworld but not seeing anything > add up to anything like 100%, including S)ystem processes, in top. [..]> > However that doesn't explain this typical top view when the system is > quiescent or nearly so, as it mostly is, with only 5-minutely crons and > 11-minutely entropy runs and the odd sendmail to be seen in lastcomm: > > last pid: 18500; load averages: 0.01, 0.08, 0.06 up 5+08:40:33 17:30:30 > 136 processes: 3 running, 110 sleeping, 23 waiting > CPU states: 5.7% user, 0.0% nice, 6.3% system, 0.0% interrupt, 88.0% idle > Mem: 73M Active, 18M Inact, 46M Wired, 8108K Cache, 25M Buf, 2572K Free > Swap: 384M Total, 106M Used, 278M Free, 27% Inuse > > PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND > 11 root 171 52 0K 8K RUN 102.3H 86.82% 86.82% idle > 743 smithi 96 0 26616K 2908K select 156:40 1.03% 1.03% kdeinit > 708 smithi 96 0 34140K 15024K select 223:05 0.63% 0.63% Xorg > 644 root 96 0 1244K 244K select 30:19 0.05% 0.05% moused > 775 smithi 20 0 11524K 1028K kserel 319:17 0.00% 0.00% xmms > It never shows more than about 90% idle, whereas a 0.01 shorter term > load average should indicate more like 99% idle, shouldn't it? 97-99%, > sometimes 100% idle was what FreeBSD 4.5-R used to tell me with the same > workload in around the same memory use, but maybe 4.5 was optimistic .. I would guess that maybe xmms (or some other threaded app) is your hidden CPU consumer. The kernel does not calculate %CPU correctly for libkse-threaded programs, and they usually show up as 0% all the time. The TIME column does update correctly, though. If you switch to libthr with libmap.conf, you'll get accurate threaded %CPU reporting. -- Dan Nelson dnelson@allantgroup.com
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