Message-ID: <3BC2B399.8030000@wipro.com>
Date: Tue, 09 Oct 2001 13:51:45 +0530
From: "BALBIR SINGH" <balbir.singh@wipro.com>
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To: dipankar@in.ibm.com
CC: "Paul E. McKenney" <pmckenne@us.ibm.com>, lse-tech@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: RFC: patch to allow lock-free traversal of lists with insertion
In-Reply-To: <200110090155.f991tPt22329@eng4.beaverton.ibm.com> <3BC2A3B3.3020004@wipro.com> <20011009131626.A10410@in.ibm.com>
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Dipankar Sarma wrote:

>On Tue, Oct 09, 2001 at 12:43:55PM +0530, BALBIR SINGH wrote:
>
>>1) On Alpha this code does not improve performance since we end up using spinlocks
>>for my_global_data anyway, I think you already know this.
>>
>
>It may if you don't update very often. It depends on your
>read-to-write ratio.
>
>>The approach is good, but what are the pratical uses of the approach. Like u mentioned a newly
>>added element may not show up in the search, searches using this method may have to search again
>>and there is no way of guaranty that an element that we are looking for will be found (especially
>>if it is just being added to the list).
>>
>>The idea is tremendous for approaches where we do not care about elements being newly added.
>>It should definitely be in the Linux kernel  :-) 
>>
>
>Either you see the element or you don't. If you want to avoid duplication,
>you could do a locked search before inserting it.
>Like I said before, lock-less lookups are useful for read-mostly
>data. Yes, updates are costly, but if they happen rarely, you still benefit.
>
How does this compare to the Read-Copy-Update mechanism? Is this just another way of implementing
it, given different usage rules.

Balbir


>
>Thanks
>Dipankar
>


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