Messages in this thread | | | Date | Mon, 23 May 2011 18:26:23 -0700 | From | Yinghai Lu <> | Subject | Re: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" |
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On 05/23/2011 06:18 PM, Paul E. McKenney wrote:
> OK, so it looks like I need to get this out of the way in order to track > down the delays. Or does reverting PeterZ's patch get you a stable > system, but with the longish delays in memory_dev_init()? If the latter, > it might be more productive to handle the two problems separately. > > For whatever it is worth, I do see about 5% increase in grace-period > duration when switching to kthreads. This is acceptable -- your > 30x increase clearly is completely unacceptable and must be fixed. > Other than that, the main thing that affects grace period duration is > the setting of CONFIG_HZ -- the smaller the HZ value, the longer the > grace-period duration.
for my 1024g system when memory hotadd is enabled in kernel config: 1. current linus tree + tip tree: memory_dev_init will take about 100s. 2. current linus tree + tip tree + your tree - Peterz patch: a. on fedora 14 gcc: will cost about 4s: like old times b. on opensuse 11.3 gcc: will cost about 10s.
Thanks
Yinghai Lu
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