Re: Proposal of tunable fix for scalability of 8.4

On 03/12/09 11:13, Kevin Grittner wrote:
>>>> Scott Carey <scott(at)richrelevance(dot)com> wrote:
>>>>
>> "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
>>
>>
>>> I'm a lot more interested in what's happening between 60 and 180
>>> than over 1000, personally. If there was a RAID involved, I'd put
>>> it down to better use of the numerous spindles, but when it's all
>>> in RAM it makes no sense.
>>>
>> If there is enough lock contention and a common lock case is a short
>> lived shared lock, it makes perfect sense sense. Fewer readers are
>> blocked waiting on writers at any given time. Readers can 'cut' in
>> line ahead of writers within a certain scope (only up to the number
>> waiting at the time a shared lock is at the head of the queue).
>> Essentially this clumps up shared and exclusive locks into larger
>> streaks, and allows for higher shared lock throughput.
>>
>
> You misunderstood me. I wasn't addressing the affects of his change,
> but rather the fact that his test shows a linear improvement in TPS up
> to 1000 connections for a 64 thread machine which is dealing entirely
> with RAM -- no disk access. Where's the bottleneck that allows this
> to happen? Without understanding that, his results are meaningless.
>
> -Kevin
>
>

Every user has a think time (200ms) to wait before doing the next
transaction which results in idle time and theoretically allows other
users to run in between ..

-Jignesh