Re: [boost] Re: Smart pointers: One more implementation +question

From: Pavel Vasiliev (pavel_at_[hidden])
Date: 2003-02-07 09:00:45

Alexander Terekhov wrote:

> Pavel Vasiliev wrote:
> [...]
>> I really think that having the only mutex for all short smart
>> pointer-related interlocked operations will not harm performance of
>> real-life applications in mp systems. In my code this mutex is used
>> only for really short operations like "lock, increment, save to
>> temporary, unlock, test the temporary". It is hard to imagine that
>> contention will often occur for so short operations.

> Well, "raw" contention aside, with "ping-pong" I mean that with your
> design clients might rather quickly get into trouble with respect to 
> "false sharing" effect(s) -- writing to "cache line" that is also 
> held by another processor. The problem here is rather expensive 
> communications needed to invalidate the other processor's cache-line, 
> feed it with "up-to-date" data [that's most likely an additional 
> "slow trip" to memory], etc. Well, you might want to take a look at: 

> < "Performance Management Guide" [AIX 5L Version 5.1] >

> http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixbman/prftungd/2365c31.htm#HDRI42667
> (Lock Granularity)

> http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixbman/prftungd/2365c31.htm#HDRI26126
> (Cache Coherency)

> http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixbman/prftungd/2365c33.htm#HDRI14109
> (Multiprocessor Throughput Scalability)

> < etc. "general" stuff from this publication >

Thank you!

I'll probably have more suggestions after reading these articles.

Pavel