Messages in this thread | | | Date | Mon, 2 Sep 2013 17:00:15 +0300 | From | Sergey Senozhatsky <> | Subject | Re: [sched next] overflowed cpu time for kernel threads in /proc/PID/stat |
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On (09/02/13 15:50), Stanislaw Gruszka wrote: > Date: Mon, 2 Sep 2013 15:50:34 +0200 > From: Stanislaw Gruszka <sgruszka@redhat.com> > To: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, Ingo Molnar > <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>, "Paul E. > McKenney" <paulmck@linux.vnet.ibm.com>, Borislav Petkov <bp@alien8.de>, > linux-kernel@vger.kernel.org > Subject: Re: [sched next] overflowed cpu time for kernel threads in > /proc/PID/stat > User-Agent: Mutt/1.5.21 (2010-09-15) > > On Mon, Sep 02, 2013 at 03:07:45PM +0200, Frederic Weisbecker wrote: > > > Hope this may help. > > > I've added a silly check to make sure that `stime < rtime' > > > > > > @@ -579,6 +582,10 @@ static void cputime_adjust(struct task_cputime *curr, > > > if (total) { > > > stime = scale_stime((__force u64)stime, > > > (__force u64)rtime, (__force u64)total); > > > + if (stime > rtime) { > > > + printk(KERN_ERR "Ooops: stime:%llu rtime:%llu\n", stime, rtime); > > > + WARN_ON(1); > > > + } > > > utime = rtime - stime; > > > } else { > > > stime = rtime; > [snip] > > > Thanks a lot Sergey for testing this further! > > > > Interesting results, so rtime is always one or two units off stime after scaling. > > Stanislaw made the scaling code with Linus and he has a better idea on the math guts > > here. > > I don't think this is scale issue, but rather at scale_stime() input > stime is already bigger then rtime. Sergey, could you verify that > by adding check before scale_stime() ? >
usually stime < rtime. this is what scale_stime() gets as input:
[ 1291.409566] stime:3790580815 rtime:4344293130 total:3790580815 [ 1300.484675] stime:3966526699 rtime:4316110636 total:3966526699 [ 1309.548850] stime:4016453845 rtime:4369061182 total:4016453845 [ 1315.597880] stime:4055256777 rtime:4409603756 total:4055256777 [ 1315.598340] stime:4004230541 rtime:4571167362 total:4004230541 [ 1318.623774] stime:4072651687 rtime:4427641260 total:4072651687 [ 1318.624194] stime:3307672697 rtime:4359433252 total:3307672697 [ 1321.661950] stime:4073588267 rtime:4644946914 total:4073588267 [ 1324.691457] stime:4105876887 rtime:4462631018 total:4105876887 [ 1327.722074] stime:3375231967 rtime:4439900096 total:3375231967 [ 1333.757482] stime:4156087279 rtime:4514990216 total:4156087279 [ 1333.757755] stime:3427423145 rtime:4504337498 total:3427423145 [ 1333.758080] stime:4180115893 rtime:4758073724 total:4180115893 [ 1339.813117] stime:3465843945 rtime:4554325330 total:3465843945 [ 1342.845746] stime:4204665773 rtime:4565346324 total:4204665773 [ 1345.888570] stime:3497346343 rtime:4592210094 total:3497346343 [ 1348.922371] stime:4348957782 rtime:4935439460 total:4348957782 [ 1351.950096] stime:4362056506 rtime:4949617939 total:4362056506 [ 1361.021453] stime:4295785738 rtime:4661661137 total:4295785738 [ 1361.022000] stime:4458897246 rtime:5051395981 total:4458897246 [ 1364.050371] stime:4311972683 rtime:4678581654 total:4311972683 [ 1364.050765] stime:4479087426 rtime:5072949454 total:4479087426 [ 1367.076973] stime:4499465526 rtime:5094687861 total:4499465526 [ 1370.099987] stime:4343775870 rtime:4712036053 total:4343775870 [ 1373.125650] stime:4359154163 rtime:4727095545 total:4359154163 [ 1373.126009] stime:4552630150 rtime:5150626456 total:4552630150 [ 1376.148541] stime:4374640011 rtime:4743265121 total:4374640011 [ 1379.177031] stime:3732027459 rtime:4887067184 total:3732027459 [ 1382.220666] stime:4404735122 rtime:4774829507 total:4404735122 [ 1385.246696] stime:4420289930 rtime:4790957716 total:4420289930 [ 1385.247197] stime:4649961982 rtime:5253432805 total:4649961982 [ 1388.269661] stime:4433706951 rtime:4804365472 total:4433706951 [ 1388.270078] stime:3783514895 rtime:4952742424 total:3783514895 [ 1391.299533] stime:4449952651 rtime:4821791998 total:4449952651 [ 1394.329016] stime:4463714342 rtime:4836891922 total:4463714342
-ss
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