From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 5 Sep 2008 20:17:54 +0200 From: Ingo Molnar Subject: Re: [PATCH] [RESEND] x86_64: add memory hotremove config option Message-ID: <20080905181754.GA14258@elte.hu> References: <20080905172132.GA11692@us.ibm.com> <20080905174449.GC27395@elte.hu> <1220638478.25932.20.camel@badari-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1220638478.25932.20.camel@badari-desktop> Sender: owner-linux-mm@kvack.org Return-Path: To: Badari Pulavarty Cc: Gary Hade , linux-mm@kvack.org, Andrew Morton , Yasunori Goto , Mel Gorman , Chris McDermott , linux-kernel@vger.kernel.org, x86@kernel.org List-ID: * Badari Pulavarty wrote: > > On Fri, 2008-09-05 at 19:44 +0200, Ingo Molnar wrote: > > * Gary Hade wrote: > > > > > Add memory hotremove config option to x86_64 > > > > > > Memory hotremove functionality can currently be configured into the > > > ia64, powerpc, and s390 kernels. This patch makes it possible to > > > configure the memory hotremove functionality into the x86_64 kernel as > > > well. > > > > hm, why is it for 64-bit only? > > > > > +++ linux-2.6.27-rc5/arch/x86/Kconfig 2008-09-03 13:34:55.000000000 -0700 > > > @@ -1384,6 +1384,9 @@ > > > def_bool y > > > depends on X86_64 || (X86_32 && HIGHMEM) > > > > > > +config ARCH_ENABLE_MEMORY_HOTREMOVE > > > + def_bool y > > > > so this will break the build on 32-bit, if CONFIG_MEMORY_HOTREMOVE=y? > > mm/memory_hotplug.c assumes that remove_memory() is provided by the > > architecture. > > > > > +#ifdef CONFIG_MEMORY_HOTREMOVE > > > +int remove_memory(u64 start, u64 size) > > > +{ > > > + unsigned long start_pfn, end_pfn; > > > + unsigned long timeout = 120 * HZ; > > > + int ret; > > > + start_pfn = start >> PAGE_SHIFT; > > > + end_pfn = start_pfn + (size >> PAGE_SHIFT); > > > + ret = offline_pages(start_pfn, end_pfn, timeout); > > > + if (ret) > > > + goto out; > > > + /* Arch-specific calls go here */ > > > +out: > > > + return ret; > > > +} > > > +EXPORT_SYMBOL_GPL(remove_memory); > > > +#endif /* CONFIG_MEMORY_HOTREMOVE */ > > > > hm, nothing appears to be arch-specific about this trivial wrapper > > around offline_pages(). > > Yes. All the archs (ppc64, ia64, s390, x86_64) have exact same > function. No architecture needed special handling so far (initial > versions of ppc64 needed extra handling, but I moved the code > to different place). > > We can make this generic and kill all arch-specific ones. > Initially, we didn't know if any arch needs special handling - > so ended up having private functions for each arch. > I think its time to merge them all. > > > Shouldnt this be moved to the CONFIG_MEMORY_HOTREMOVE portion of > > mm/memory_hotplug.c instead, as a weak function? That way architectures > > only have to enable ARCH_ENABLE_MEMORY_HOTREMOVE - and architectures > > with different/special needs can override it. > > Yes. We should do that. I will send out a patch. ok - if all architectures have the same function then please make it a regular function not a weak one, and remove all the duplications. Ingo -- 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