Re: 2.6.39-rc4+: Kernel leaking memory during FS scanning,regression?

[Mike Galbraith]

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]                                                                                                            


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