From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx136.postini.com [74.125.245.136]) by kanga.kvack.org (Postfix) with SMTP id 8DE3C6B006C for ; Wed, 2 Jan 2013 20:16:58 -0500 (EST) From: Rusty Russell Subject: Re: [PATCH 06/13] cpuset: cleanup cpuset[_can]_attach() In-Reply-To: <20130102153439.GA11220@mtj.dyndns.org> References: <1354138460-19286-1-git-send-email-tj@kernel.org> <1354138460-19286-7-git-send-email-tj@kernel.org> <50DACF5B.6050705@huawei.com> <20121226120415.GA18193@mtj.dyndns.org> <87zk0s5h7c.fsf@rustcorp.com.au> <20130102153439.GA11220@mtj.dyndns.org> Date: Thu, 03 Jan 2013 11:17:11 +1030 Message-ID: <871ue35bzk.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Li Zefan , paul@paulmenage.org, glommer@parallels.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, peterz@infradead.org, mhocko@suse.cz, bsingharora@gmail.com, hannes@cmpxchg.org, kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Tejun Heo writes: > Hello, Rusty. > > On Wed, Jan 02, 2013 at 03:12:15PM +1030, Rusty Russell wrote: >> > Hmmm? cpumask_t can't be used for stack but other than that I don't >> > see how it would be deprecated completely. Rusty, can you please >> > chime in? >> >> The long-never-quite-complete-plan was for struct cpumask to be >> undefined when CONFIG_CPUMASK_OFFSTACK=y. That means noone can declare >> them, or pass them on the stack, since they'll get a compiler error. >> >> Now, there are some cases where it really is a reason to use a static >> bitmap, and 1/2 a K of wasted space be damned. There's a >> deliberately-ugly way of doing that: declare a bitmap and use >> to_cpumask(). Of course, if we ever really want to remove NR_CPUS and >> make it completely generic, we have to kill all these too, but noone is >> serious about that. > > So, I guess this currently is caught in a place which isn't here or > there. I'm pretty skeptical whether it makes sense to bother about > static usages tho. Can I keep them for static ones? I didn't realize that cpuset_attach was a fastpath. If it is, put a static there and I'll fix turn it into a bitmap when I need to. Otherwise, please don't change the code in the first place. Cheers, Rusty. -- 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