fadvise DONTNEED implementation (or lack thereof)

[Brian K. White]

On 11/14/2010 12:20 AM, Ben Gamari wrote:
> On Sun, 14 Nov 2010 14:09:29 +0900 (JST), KOSAKI Motohiro<kosaki.motohiro at jp.fujitsu.com>  wrote:
>> Because we have an alternative solution already. please try memcgroup :)
>>
> Alright, fair enough. It still seems like there are many cases where
> fadvise seems more appropriate, but memcg should at least satisfy my
> personal needs so I'll shut up now. Thanks!
>
> - Ben

Could someone expand on this a little?

The "there are no users of this feature" argument is indeed a silly one. 
I've only wanted the ability to perform i/o without poisoning the cache 
since oh, 10 or more years ago at least. It really hurts my users since 
they are all direct login interactive db app users. No load balancing 
web interface can hide the fact when a box goes to a crawl.

How would one use memcgroup to prevent a backup or other large file 
operation from wiping out the cache with used-once garbage?

(note for rsync in particular, how does this help rsync on other platforms?)

-- 
bkw