linux-kernel - Re: [ckrm-tech] [PATCH] BC: resource beancounters (v4) (added user memory)

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: <450E5813.2040804@in.ibm.com>
Date:	Mon, 18 Sep 2006 13:55:55 +0530
From:	Balbir Singh <balbir@...ibm.com>
To:	Pavel Emelianov <xemul@...nvz.org>
Cc:	sekharan@...ibm.com, Srivatsa <vatsa@...ibm.com>,
	Rik van Riel <riel@...hat.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	CKRM-Tech <ckrm-tech@...ts.sourceforge.net>,
	Dave Hansen <haveblue@...ibm.com>, Andi Kleen <ak@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@...radead.org>,
	Andrey Savochkin <saw@...ru>,
	Matt Helsley <matthltc@...ibm.com>,
	Hugh Dickins <hugh@...itas.com>,
	Alexey Dobriyan <adobriyan@...l.ru>,
	Kirill Korotaev <dev@...ru>, Oleg Nesterov <oleg@...sign.ru>,
	devel@...nvz.org
Subject: Re: [ckrm-tech] [PATCH] BC: resource beancounters (v4) (added	user
 memory)

Pavel Emelianov wrote:
> Kirill Korotaev wrote:
> 
> [snip]
>>> I have a C program that computes limits to obtain desired guarantees
>>> in a single 'for (i = 0; i < n; n++)' loop for any given set of guarantees.
>>> With all error handling, beautifull output, nice formatting etc it weights
>>> only 60 lines.
> 
> Look at http://wiki.openvz.org/Containers/Guarantees_for_resources
> I've described there how a guarantee can be get with limiting in details.
> 
> [snip]
> 
>>> I do not 'do not like guarantee'. I'm just sure that there are two ways
>>> for providing guarantee (for unreclaimable resorces):
>>> 1. reserving resource for group in advance
>>> 2. limit resource for others
>>> Reserving is worse as it is essentially limiting (you cut off 100Mb from
>>> 1Gb RAM thus limiting the other groups by 900Mb RAM), but this limiting
>>> is too strict - you _have_ to reserve less than RAM size. Limiting in
>>> run-time is more flexible (you may create an overcommited BC if you
>>> want to) and leads to the same result - guarantee.
>> I think this deserves putting on Wiki.
>> It is very good clear point.
> 
> This is also on the page I gave link at.
> 

This approach has the following disadvantages
  1. Lets consider initialization - When we create 'n' groups initially, we need
     to spend O(n^2) time to assign guarantees.
  2. Every time a limit or a guarantee changes, we need to recalculate guarantees
     and ensure that the change will not break any guarantees
  3. The same thing as stated above, when a resource group is created or deleted

This can lead to some instability; a change in one group propagates to all other groups.


-- 

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs
-
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/