Alexander Viro wrote:
>
>On Tue, 29 Jan 2002, Hans Reiser wrote:
>
>>This fails to recover an object (e.g. dcache entry) which is used once,
>>and then spends a year in cache on the same page as an object which is
>>hot all the time. This means that the hot set of objects becomes
>>diffused over an order of magnitude more pages than if garbage
>>collection squeezes them all together. That makes for very poor caching.
>>
>
>Any GC that is going to move active dentries around is out of question.
>It would need a locking of such strength that you would be the first
>to cry bloody murder - about 5 seconds after you look at the scalability
>benchmarks.
>
>
I don't mean to suggest that the dentry cache locking is an easy problem
to solve, but the problem discussed is a real one, and it is sufficient
to illustrate that the unified cache is fundamentally flawed as an
algorithm compared to using subcache plugins.
Hans
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This archive was generated by hypermail 2b29 : Thu Jan 31 2002 - 21:00:59 EST