Re: ice-broker scan thread

[David Boreham <david_list(at)boreham(dot)org>]

> Yes. The O_DIRECT issue is my biggest concern about Linux at the moment.
> That being said, the plan is to only pre-fetch the next N blocks, where N
> < 32, and to read them into the local buffer cache. In a situation where
> space in the cache low (and prefetched pages might be pushed out before we
> even get to read them), we need to provide such information to the
> readahead mechanism so that it can reduce the number of blocks which it
> prefetches.
>
>
>  
Would you open a separate handle O_DIRECT, just for the prefetch ?

My experience with O_DIRECT and databases in the past has not been
great : what you gain with being able to control your own caching you loose
(and more) in other ways.

BTW, has anyone tried O_DIRECT and the prefetch idea on Linux ?
I'm wondering if it may not work (because the read data won't get cached
in the fs cache due to O_DIRECT).