From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by e28esmtp07.in.ibm.com (8.13.1/8.13.1) with ESMTP id m1KGJVIc019331 for ; Wed, 20 Feb 2008 21:49:31 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m1KGJVMc340112 for ; Wed, 20 Feb 2008 21:49:31 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.13.1/8.13.3) with ESMTP id m1KGJUpY031717 for ; Wed, 20 Feb 2008 16:19:31 GMT Message-ID: <47BC5211.6030102@linux.vnet.ibm.com> Date: Wed, 20 Feb 2008 21:45:13 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [PATCH] Document huge memory/cache overhead of memory controller in Kconfig References: <20080220122338.GA4352@basil.nowhere.org> <47BC2275.4060900@linux.vnet.ibm.com> <18364.16552.455371.242369@stoffel.org> <47BC4554.10304@linux.vnet.ibm.com> <18364.20755.798295.881259@stoffel.org> In-Reply-To: <18364.20755.798295.881259@stoffel.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: John Stoffel Cc: Jan Engelhardt , Andi Kleen , akpm@osdl.org, torvalds@osdl.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: John Stoffel wrote: >>>>>> "Jan" == Jan Engelhardt writes: > > Jan> On Feb 20 2008 20:50, Balbir Singh wrote: >>> John Stoffel wrote: >>>> I know this is a pedantic comment, but why the heck is it called such >>>> a generic term as "Memory Controller" which doesn't give any >>>> indication of what it does. >>>> >>>> Shouldn't it be something like "Memory Quota Controller", or "Memory >>>> Limits Controller"? >>> It's called the memory controller since it controls the amount of >>> memory that a user can allocate (via limits). The generic term for >>> any resource manager plugged into cgroups is a controller. > > Jan> For ordinary desktop people, memory controller is what developers > Jan> know as MMU or sometimes even some other mysterious piece of > Jan> silicon inside the heavy box. > > That's what was confusing me at first. I was wondering why we needed > a memory controller when we already had one in Linux! > > Also, controlling a resource is more a matter of limits or quotas, not > controls. Well, I'll actually back off on that, since controls does > have a history in other industries. > > But for computers, limits is an expected and understood term, and for > filesystems it's quotas. So in this case, I *still* think you should > be using the term "Memory Quota Controller" instead. It just makes it > clearer to a larger audience what you mean. > Memory Quota sounds very confusing to me. Usually a quota implies limits, but in a true framework, one can also implement guarantees and shares. >>> If you look through some of the references in the document, we've >>> listed our plans to support other categories of memory as well. >>> Hence it's called a memory controller >>> >>>> Also, the Kconfig name "CGROUP_MEM_CONT" is just wrong, it should >>>> be "CGROUP_MEM_CONTROLLER", just spell it out so it's clear what's >>>> up. > >>> This has some history as well. Control groups was called containers >>> earlier. That way a name like CGROUP_MEM_CONT could stand for >>> cgroup memory container or cgroup memory controller. > > Jan> CONT is shorthand for "continue" ;-) (SIGCONT, f.ex.), ctrl or > Jan> ctrlr it is for controllers (comes from Solaris iirc.) > > Right, CTLR would be more regular shorthand for CONTROLLER. > > Basically, I think you're overloading a commonly used term for your > own uses and when it's exposed to regular users, it will cause > confusion. > OK, I'll queue a patch and try to explain various terms used by resource management. > Thanks, > John -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- 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