Re: [Firebird-devel] Firebird 3.0.1 - SuperServer - Scalability

[Thomas S. <ts...@ib...>]

Hello Vlad,

> 14.11.2016 16:09, Thomas Steinmaurer wrote:
>> Hello Simon,
>>
>>> Thomas Steinmaurer <ts...@ib...> wrote Mon, 14 Nov 2016 15:03:41
>>> +0300:
>>>
>>>> Hello,
>>>>
>>>> using Firebird-3.0.1.32609-0_x64_pdb.zip SuperServer on Windows 10 Prof.
>>>> with 16G RAM, spinning disk (7200K) and Xeon 1230 CPU (4 physical cores)
>>>>
>>>> Performance related changes in firebird.conf are:
>>>>
>>>> DB Page Size = 8K
>>>> DefaultDbCachePages = 128K (DB specific page buffers = 0)
>
>    Here you disabled file system cache (as Denis already said)

Ok.

So, with 16G RAM and an OLTP emul database with ~ 2,9G, it is still 
recommended with Firebird 3 SS and the shared page cache, to rather use 
a smaller number, lets say 50K and keep the FileSystemCacheThreshold at 
64K to have the file system cache enabled? Or e.g. increase both 
DefaultDbCachePages and FileSystemCacheThreshold?

The main question is how to utilize cheap and available RAM best.

>>>> TempCacheLimit = 1024M
>>>> LockHashSlots = 22111
>>>>
>>>> anything else is default (except TCP port).
>>>>
>>>
>>> Try to install FileSystemCacheThreshold > DefaultDbCachePages.
>>> If FileSystemCacheThreshold < DefaultDbCachePages file cache is disabled,
>>> which may reduce performance ability to make some cases.
>>
>>  From my understanding, file system cache is much more important for
>> SC/CS than with a large single page cache in SS. Is this assumption wrong?
>
>    SS requires less support from file system cache for reads but still need it
> for writes, especially in OLTP environment.

Why writes in particular?

Regards,
Thomas

>
> The best case when current Firebird could work better without support of file
> system cache is when:
> - mostly read load
> - working set fits into page cache
> - database page cache is preloaded (using "select count(*)" for example)
>
> Regards,
> Vlad
>
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