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Re: Lock-free databases

From: Joe Seigh <jseigh_01_at_xemaps.com>
Date: Wed, 09 Nov 2005 12:20:37 -0500
Message-ID: <cNadnT7vK4ctsu_enZ2dnUVZ_tSdnZ2d@comcast.com>


vc wrote:
> Joe Seigh wrote:
>

>>vc wrote:
>>>
>>>Since they "haven't provided any facts significant to anyone familiar
>>>with lock-free programming techniques",  how can you claim that "
>>>Lock-free techniques similar to the ones covered by their patents have
>>>be used in operating system kernels for decades and those operating
>>>systems weren't going around proclaiming they were lock-free".
>>>
>>
>>Because I used to be a mainframe kernel developer and implemented
>>some of those lock-free algorithms.  In fact I did an RCU implementation
>>in the mid 80's.

>
>
> 1. How does your being familiar with some lock-free algorithms and
> having implemented others let you *know* what specific lock-free
> algorithms ANTs uses (unless you familiar with the patents in question
> in which case there is a contradiction with your other statement that
> they "haven't provided any facts significant to anyone familiar with
> lock-free programming techniques") ?

They haven't quantified the performance contribution of the patents and knowing the techniques in question, they'd have to have some very specific performance bottlenecks to get a significant benefit.
>
> 2. For my own education, while I am aware that IBM/370 had the compare
> and swap instruction (as well as 'test and set') , what specific
> lock-free algorithms, other than multiprocessing support, were
> implemented in the mainframe kernel 20-30 years ago ?
>

Lock-free LIFO queues and lock-free enqueuing onto FIFO queues. Some fast pathed things like WAIT/POST bypass. Examples of those were in appendix A for the 370/390/z-Arch Principles of Operation. And an RCU like mechanism in the VM operating system. Those would be the main ones that I can think of offhand.

-- 
Joe Seigh

When you get lemons, you make lemonade.
When you get hardware, you make software. 
Received on Wed Nov 09 2005 - 11:20:37 CST

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