Re: [Firebird-devel] AutoOptimize

[= m. Th = <th...@va...>]

Vlad Horsun wrote:
> ....
>     Ideally this threads must run with such priority to not harm other threads.
> If we have IO subsystem which can handle, say, N IO requests per second,
> and constant work load with M IO requests per second (M < N), we can safely
> let background (or low IO priority) threads perform N - M IO requests per second.
> Am i wrong ?
> Problem is that we don't know N and M
>
>   
>> Certainly, we can invite 
>> a lot - let single request pass after N high-priority requests provided 
>> total requests number is less or equal to M. Having M and N settable 
>> from firebird.conf:). Do we need such overcomplicated things?
>>     
>
>     If it will work than yes we need it ;) But i doubt such algorithm will work well
>  
> ...
>   
Can you explain please why you think that this will not work well? 
Because similar algorithms (ie. prioritized queues) are the basis on 
today networks. IMHO, the scope is the same prioritizing/managing access 
to a slow resource. For ex. see 
http://en.wikipedia.org/wiki/Quality_of_service as a start.

Also, IMHO, is very good to have a look at 
http://en.wikipedia.org/wiki/Background_Intelligent_Transfer_Service - 
we need something like this, but for disks, right?

As an aside it seems a little bit odd that while we have a resource 
hungry feature triggering in the way in which GC triggers which can 
reach to the point of exhausting server memory (see the thread 'Firebird 
restarting' from the support list) and we are a little bit 'scared' 
about statistics auto updating. But, overall, the discussion is very 
good, and IMHO many good things arise which you can use elsewhere. Just 
not to forget that while is very good to have such 'automatic' things 
(lower TCO & TTM, good behaviour out-of-the-box, attract new users) and 
profile them, we'll never to cover all the situations and we need to 
allow a 'knob' to shut the feature off/on without restarting the server, 
if the user wants.


hth,

m. th.