Re: adding support for posix_fadvise()

Neil Conway wrote:

>The present Linux implementation doesn't do this, AFAICS -- all it does
>it increase the readahead for this file:
>  
>
AFAIK Linux uses a modified LRU that automatically puts pages that were 
touched only once at a lower priority than frequently accessed pages.

Neil: what about calling posix_fadvise for the whole file immediately 
after issue_xlog_fsync() in XLogWrite? According to the comment, it's 
guaranteed that this will happen only once.
Or:  add an posix_fadvise into issue_xlog_fsync(), for the range just 
sync'ed.

Btw, how much xlog traffic does a busy postgres site generate?

--   Manfred