Messages in this thread |  | | Date | Thu, 12 May 2011 18:28:45 -0700 | | From | Yinghai Lu <> | | Subject | Re: [GIT PULL rcu/next] rcu commits for 2.6.40 |
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On 05/12/2011 02:36 PM, Yinghai Lu wrote: > On 05/12/2011 02:20 AM, Paul E. McKenney wrote: >> On Thu, May 12, 2011 at 12:42:50AM -0700, Yinghai Lu wrote: >>> On 05/12/2011 12:27 AM, Yinghai Lu wrote: >>>> On 05/11/2011 11:03 PM, Ingo Molnar wrote: >>>>> >>>>> * Yinghai Lu <yinghai@kernel.org> wrote: >>>>> >>>>>> e59fb3120becfb36b22ddb8bd27d065d3cdca499 is the first bad commit >>>>>> commit e59fb3120becfb36b22ddb8bd27d065d3cdca499 >>>>>> Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> >>>>>> Date: Tue Sep 7 10:38:22 2010 -0700 >>>>>> >>>>>> rcu: Decrease memory-barrier usage based on semi-formal proof >>>>> >>>>> Find below an (untested!) attempt at reverting it for debugging purposes: could >>>>> you please try it, does your system now boot up fine? >>>>> >>>>> Thanks, >>>>> >>>>> Ingo >>>>> >>>> >>>> yes, reverted manually that commit fix the problem. >>> >>> on system with 8 sockets westmere-ex >>> >>> it seems other commits after that commit contribute some delay too. >>> >>> [ 32.240739] cpu_dev_init done >>> [ 73.587288] memory_dev_init done >> >> I am testing a revert of e59fb3120becfb36b22ddb8bd27d065d3cdca499 and >> will chase down the delay. >> > > it seems still need to revert following one in addition e59fb3120becfb36b22ddb8bd27d065d3cdca499. > > [root@mpk14-2404-239-158 linux-2.6]# git bisect good > a26ac2455ffcf3be5c6ef92bc6df7182700f2114 is the first bad commit > commit a26ac2455ffcf3be5c6ef92bc6df7182700f2114 > Author: Paul E. McKenney <paul.mckenney@linaro.org> > Date: Wed Jan 12 14:10:23 2011 -0800 > > rcu: move TREE_RCU from softirq to kthread > > If RCU priority boosting is to be meaningful, callback invocation must > be boosted in addition to preempted RCU readers. Otherwise, in presence > of CPU real-time threads, the grace period ends, but the callbacks don't > get invoked. If the callbacks don't get invoked, the associated memory > doesn't get freed, so the system is still subject to OOM. > > But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit > moves the callback invocations to a kthread, which can be boosted easily. > > Also add comments and properly synchronized all accesses to > rcu_cpu_kthread_task, as suggested by Lai Jiangshan. > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Reviewed-by: Josh Triplett <josh@joshtriplett.org> > > :040000 040000 e40306ac6405952c1d387325a98588442209abe8 efe9ea2f408c62daaccf49e6d1339dff3a74f049 M Documentation > :040000 040000 8f9e7a8fa3a728d4ae58e2efb8ada7cf08aed00e 9b44deba45ba905c5d9b3cc314812f0ba3f7e639 M include > :040000 040000 4b10b719a2d56ed4bc796a9f43775732bb5ff144 4db269277ccf607e1a6a7d7f4c2a7cf8d592d46a M kernel > :040000 040000 881f102e6831381beed016ed240d690f6a2ccd5e 57d2fc6f84e47394c116bc617a9a0ef9b8b6dbd4 M tools
more info: if only reverting: e59fb3120becfb36b22ddb8bd27d065d3cdca499
when compiled with gcc from opensuse 11.3 [ 32.579585] cpu_dev_init done [ 81.203193] memory_dev_init done
but when compile that with gcc from fedora 14, then will less delay. [ 32.404140] cpu_dev_init done [ 37.602986] memory_dev_init done
gcc version on opensuse 11.3 gcc (SUSE Linux) 4.5.0 20100604 [gcc-4_5-branch revision 160292]
gcc version on fedora 14: gcc (GCC) 4.5.1 20100924 (Red Hat 4.5.1-4)
Thanks
Yinghai
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