On Thu, Apr 28, 2011 at 5:28 PM, Sedat Dilek wrote: > On Thu, Apr 28, 2011 at 3:30 PM, Mike Galbraith wrote: >> On Thu, 2011-04-28 at 03:26 -0700, Paul E. McKenney wrote: >>> On Thu, Apr 28, 2011 at 11:45:03AM +0200, Sedat Dilek wrote: >>> > Hi, >>> > >>> > not sure if my problem from linux-2.6-rcu.git#sedat.2011.04.23a is >>> > related to the issue here. >>> > >>> > Just FYI: >>> > I am here on a Pentium-M (uniprocessor aka UP) and still unsure if I >>> > have the correct (optimal?) kernel-configs set. >>> > >>> > Paul gave me a script to collect RCU data and I enhanced it with >>> > collecting SCHED data. >>> > >>> > In the above mentionned GIT branch I applied these two extra commits >>> > (0001 requested by Paul and 0002 proposed by Thomas): >>> > >>> > patches/0001-Revert-rcu-restrict-TREE_RCU-to-SMP-builds-with-PREE.patch >>> > patches/0002-sched-Add-warning-when-RT-throttling-is-activated.patch >>> > >>> > Furthermore, I have added my kernel-config file, scripts, patches and >>> > logs (also output of 'cat /proc/cpuinfo'). >>> > >>> > Hope this helps the experts to narrow down the problem. >>> >>> Yow!!! >>> >>> Now this one might well be able to hit the 950 millisecond limit. >>> There are no fewer than 1,314,958 RCU callbacks queued up at the end of >>> the test.  And RCU has indeed noticed this and cranked up the number >>> of callbacks to be handled by each invocation of rcu_do_batch() to >>> 2,147,483,647.  And only 15 seconds earlier, there were zero callbacks >>> queued and the rcu_do_batch() limit was at the default of 10 callbacks >>> per invocation. >> >> Yeah, yow.  Once the RT throttle hit, it stuck. >> >>  .clock                         : 1386824.201768 >>  .rt_nr_running                 : 2 >>  .rt_throttled                  : 1 >>  .rt_time                       : 950.132427 >>  .rt_runtime                    : 950.000000 >>           rcuc0     7         0.034118     10857    98         0.034118      1472.309646         0.000000 / >> FF    1      1 R    R 0 [rcuc0] >>  .clock                         : 1402450.997994 >>  .rt_nr_running                 : 2 >>  .rt_throttled                  : 1 >>  .rt_time                       : 950.132427 >>  .rt_runtime                    : 950.000000 >>           rcuc0     7         0.034118     10857    98         0.034118      1472.309646         0.000000 / >> FF    1      1 R    R 0 [rcuc0] >> >> ... >> >>  .clock                         : 2707432.862374 >>  .rt_nr_running                 : 2 >>  .rt_throttled                  : 1 >>  .rt_time                       : 950.132427 >>  .rt_runtime                    : 950.000000 >>           rcuc0     7         0.034118     10857    98         0.034118      1472.309646         0.000000 / >> FF    1      1 R    R 0 [rcuc0] >>  .clock                         : 2722572.958381 >>  .rt_nr_running                 : 2 >>  .rt_throttled                  : 1 >>  .rt_time                       : 950.132427 >>  .rt_runtime                    : 950.000000 >>           rcuc0     7         0.034118     10857    98         0.034118      1472.309646         0.000000 / >> FF    1      1 R    R 0 [rcuc0] >> >> > > Hi, > > OK, I tried with the patch proposed by Thomas (0003): > > patches/0001-Revert-rcu-restrict-TREE_RCU-to-SMP-builds-with-PREE.patch > patches/0002-sched-Add-warning-when-RT-throttling-is-activated.patch > patches/0003-sched-Remove-skip_clock_update-check.patch > > From the very beginning it looked as the system is "stable" due to: > >  .rt_nr_running                 : 0 >  .rt_throttled                  : 0 > > This changed when I started a simple tar-job to save my kernel > build-dir to an external USB-hdd. > From... > >  .rt_nr_running                 : 1 >  .rt_throttled                  : 1 > > ...To: > >  .rt_nr_running                 : 2 >  .rt_throttled                  : 1 > > Unfortunately, reducing all activities to a minimum load, did not > change from last known RT throttling state. > > Just noticed rt_time exceeds the value of 950 first time here: > >  .rt_nr_running                 : 1 >  .rt_throttled                  : 1 >  .rt_time                       : 950.005460 > > Full data attchached as tarball. > > - Sedat - > > P.S.: Excerpt from > collectdebugfs-v2_2.6.39-rc3-rcutree-sedat.2011.04.23a+.log (0:0 -> > 1:1 -> 2:1) > > -- > rt_rq[0]: >  .rt_nr_running                 : 0 >  .rt_throttled                  : 0 >  .rt_time                       : 888.893877 >  .rt_runtime                    : 950.000000 > > runnable tasks: >            task   PID         tree-key  switches  prio > exec-runtime         sum-exec        sum-sleep > ---------------------------------------------------------------------------------------------------------- > R            cat  2652    115108.993460         1   120 > 115108.993460         1.147986         0.000000 / > -- > rt_rq[0]: >  .rt_nr_running                 : 1 >  .rt_throttled                  : 1 >  .rt_time                       : 950.005460 >  .rt_runtime                    : 950.000000 > > runnable tasks: >            task   PID         tree-key  switches  prio > exec-runtime         sum-exec        sum-sleep > ---------------------------------------------------------------------------------------------------------- >           rcuc0     7         0.000000     56869    98 > 0.000000       981.385605         0.000000 / > -- > rt_rq[0]: >  .rt_nr_running                 : 2 >  .rt_throttled                  : 1 >  .rt_time                       : 950.005460 >  .rt_runtime                    : 950.000000 > > runnable tasks: >            task   PID         tree-key  switches  prio > exec-runtime         sum-exec        sum-sleep > ---------------------------------------------------------------------------------------------------------- >           rcuc0     7         0.000000     56869    98 > 0.000000       981.385605         0.000000 / > -- > As an addendum: First call trace is seen after: [ 651.616057] sched: RT throttling activated [ 711.616033] INFO: rcu_sched_state detected stall on CPU 0 (t=15000 jiffies) - 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