Re: Effects of setting linux block device readahead size

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От Matthew Wakeling
Тема Re: Effects of setting linux block device readahead size
Дата
Msg-id alpine.DEB.1.10.0809151717001.23198@aragorn.flymine.org
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Ответ на Re: Effects of setting linux block device readahead size  ("Scott Carey" <scott@richrelevance.com>)
Ответы Re: Effects of setting linux block device readahead size
Список pgsql-performance
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On Thu, 11 Sep 2008, Scott Carey wrote:
> Preliminary summary:
>
> readahead  |  8 conc read rate  |  1 conc read rate
> 49152  |  311  |  314
> 16384  |  312  |  312
> 12288  |  304  |  309
>  8192  |  292  |
>  4096  |  264  |
>  2048  |  211  |
>  1024  |  162  |  302
>   512  |  108  |
>   256  |  81  | 300
>     8  |  38  |

What io scheduler are you using? The anticipatory scheduler is meant to
prevent this slowdown with multiple concurrent reads.

Matthew


--
And the lexer will say "Oh look, there's a null string. Oooh, there's
another. And another.", and will fall over spectacularly when it realises
there are actually rather a lot.
         - Computer Science Lecturer (edited)

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