Messages in this thread | | | Subject | Re: [PATCH 4/5] locking/lockdep: Reuse free chain_hlocks entries | From | Waiman Long <> | Date | Fri, 13 Dec 2019 15:08:51 -0500 |
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On 12/13/19 1:47 PM, Peter Zijlstra wrote: > On Fri, Dec 13, 2019 at 01:35:05PM -0500, Waiman Long wrote: >> On 12/13/19 1:12 PM, Peter Zijlstra wrote: >>>> In this way, the wasted space will be k bytes where k is the number of >>>> 1-entry chains. I don't think merging adjacent blocks will be that >>>> useful at this point. We can always add this capability later on if it >>>> is found to be useful. >>> I'm thinking 1 entry isn't much of a chain. My brain is completely fried >>> atm, but are we really storing single entry 'chains' ? It seems to me we >>> could skip that. >>> >> Indeed, the current code can produce a 1-entry chain. I also thought >> that a chain had to be at least 2 entries. I got tripped up assuming >> that. It could be a bug somewhere that allow a 1-entry chain to happen, >> but I am not focusing on that right now. > If we need the minimum 2 entry granularity, it might make sense to spend > a little time on that. If we can get away with single entry markers, > then maybe write a comment so we'll not forget about it. > I will take a look at why an 1-entry chain happes and see if it is a bug that need to be fixed.
Cheers, Longman
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