From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <441FEF8D.7090905@yahoo.com.au> Date: Tue, 21 Mar 2006 23:20:29 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [PATCH][0/8] (Targeting 2.6.17) Posix memory locking and balanced mlock-LRU semantic References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Stone Wang Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Stone Wang wrote: > Both one of my friends(who is working on a DBMS oriented from > PostgreSQL) and i had encountered unexpected OOMs with mlock/mlockall. > I'm not sure this is a great idea. There are more conditions than just mlock that prevent pages being reclaimed. Running out of swap, for example, no swap, page temporarily pinned (in other words -- any duration from fleeting to permanent). I think something _much_ simpler could be done for a more general approach just to teach the VM to tolerate these pages a bit better. Also, supposing we do want this, I think there is a fairly significant queue of mm stuff you need to line up behind... it is probably asking too much to target 2.6.17 for such a significant change in any case. But despite all that I looked though and have a few comments ;) Kudos for jumping in and getting your hands dirty! It can be tricky code. > The patch brings Linux with: > 1. Posix mlock/munlock/mlockall/munlockall. > Get mlock/munlock/mlockall/munlockall to Posix definiton: transaction-like, > just as described in the manpage(2) of mlock/munlock/mlockall/munlockall. > Thus users of mlock system call series will always have an clear map of > mlocked areas. In what way are we not now posix compliant now? -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org