linux-kernel - Re: [PATCH v3 0/2] fadvise: support POSIX_FADV

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4E08346F.3070203@jp.fujitsu.com>
Date:	Mon, 27 Jun 2011 16:42:39 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	andrea@...terlinux.com
CC:	akpm@...ux-foundation.org, minchan.kim@...il.com, riel@...hat.com,
	peterz@...radead.org, hannes@...xchg.org,
	kamezawa.hiroyu@...fujitsu.com, aarcange@...hat.com,
	hughd@...gle.com, jamesjer@...terlinux.com, marcus@...ehost.com,
	matt@...ehost.com, tytso@....edu, shaohua.li@...el.com,
	P@...igBrady.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/2] fadvise: support POSIX_FADV_NOREUSE

>>>  POSIX_FADV_DONTNEED = drop page cache if possible
>>>  POSIX_FADV_NOREUSE = reduce page cache eligibility
>>
>> Eeek.
>>
>> Your POSIX_FADV_NOREUSE is very different from POSIX definition.
>> POSIX says,
>>
>>        POSIX_FADV_NOREUSE
>>               Specifies that the application expects to access the specified data once  and  then
>>               not reuse it thereafter.
>>
>> IfI understand correctly, it designed for calling _before_ data access
>> and to be expected may prevent lru activation. But your NORESE is designed
>> for calling _after_ data access. Big difference might makes a chance of
>> portability issue.
> 
> You're right. NOREUSE is designed to implement drop behind policy.
> 
> I'll post a new patch that will plug this logic in DONTNEED (like the
> presious version), but without breaking the old /proc/sys/vm/drop_caches
> behavior.

Great!

thanks.



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/