Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758144Ab0LBXeJ (ORCPT ); Thu, 2 Dec 2010 18:34:09 -0500 Received: from smtp-out.google.com ([74.125.121.35]:17125 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756216Ab0LBXeI (ORCPT ); Thu, 2 Dec 2010 18:34:08 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=tbKuraTfcTTPRJNn+jZM8QfF8B5SIlo104vZ/tFhx+T6xn/7nqZbesWtR3DJMXhl4W CoCmLJi3xxsFMwyaBgWg== Date: Thu, 2 Dec 2010 15:34:01 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: "Zheng, Shaohui" cc: Andrew Morton , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "lethal@linux-sh.org" , Andi Kleen , Dave Hansen , Greg KH , "Li, Haicheng" Subject: RE: [8/8, v6] NUMA Hotplug Emulator: implement debugfs interface for memory probe In-Reply-To: Message-ID: References: <20101202002716.GA13693@shaohui> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1840 Lines: 44 On Thu, 2 Dec 2010, Zheng, Shaohui wrote: > Why should we add so many interfaces for memory hotplug emulation? Because they are functionally different from real memory hotplug and we want to support different configurations such as mapping memory to a different node id or onlining physical nodes that don't exist. They are in debugfs because the emulation, unlike real memory hotplug, is used only for testing and debugging. > If so, we should create both sysfs and debugfs > entries for an online node, we are trying to add redundant code logic. > We do not need sysfs triggers for onlining a node, that already happens automatically if the memory that is being onlined has a hotpluggable node entry in the SRAT that has an offline node id. > We need not make a simple thing such complicated, Simple is beautiful, I'd prefer to rename the mem_hotplug/probe > interface as mem_hotplug/add_memory. > > /sys/kernel/debug/mem_hotplug/add_node (already exists) > /sys/kernel/debug/mem_hotplug/add_memory (rename probe as add_memory) > No, add_memory would then require these bizarre lines that you've been parsing like echo 'physical_addr=0x80000000 node_id=3' > /sys/kernel/debug/mem_hotplug/add_memory which is unnecessary if you introduce my proposal for per-node debugfs directories similar to that under /sys/devices/system/node that is extendable later if we add additional per-node triggers under CONFIG_DEBUG_FS. Adding /sys/kernel/debug/mem_hotplug/node2/add_memory that you write a physical address to is a much more robust, simple, and extendable interface. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/