Re: Effects of setting linux block device readahead size - Mailing list pgsql-performance

From James Mansion
Subject Re: Effects of setting linux block device readahead size
Date
Msg-id 48C97793.2070909@mansionfamily.plus.com
Whole thread Raw
In response to Re: Effects of setting linux block device readahead size  (Greg Smith <gsmith@gregsmith.com>)
Responses Re: Effects of setting linux block device readahead size  ("Scott Carey" <scott@richrelevance.com>)
List pgsql-performance
Greg Smith wrote:
> The point I was trying to make there is that even under impossibly
> optimal circumstances, you'd be hard pressed to blow out the disk's
> read cache with seek-dominated data even if you read a lot at each
> seek point.  That idea didn't make it from my head into writing very
> well though.
>
Isn't there a bigger danger in blowing out the cache on the controller
and causing premature pageout of its dirty pages?

If you could get the readahead to work on the drive and not return data
to the controller, that might be dandy, but I'm sceptical.

James


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