Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932234AbWHHFsL (ORCPT ); Tue, 8 Aug 2006 01:48:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932260AbWHHFsL (ORCPT ); Tue, 8 Aug 2006 01:48:11 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:4570 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S932234AbWHHFsK (ORCPT ); Tue, 8 Aug 2006 01:48:10 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrew Morton Cc: Andi Kleen , "Randy.Dunlap" , "Protasevich, Natalie" , linux-kernel@vger.kernel.org, Arjan van de Ven Subject: [PATCH] x86_64: Auto size the per cpu area. References: <20060807165512.dabefb63.akpm@osdl.org> <200608080417.59462.ak@suse.de> <20060807194159.f7c741b5.akpm@osdl.org> <1155005284.3042.11.camel@laptopd505.fenrus.org> Date: Mon, 07 Aug 2006 23:47:23 -0600 In-Reply-To: <1155005284.3042.11.camel@laptopd505.fenrus.org> (Arjan van de Ven's message of "Tue, 08 Aug 2006 04:47:49 +0200") Message-ID: User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2113 Lines: 67 Now for a completely different but trivial approach. I just boot tested it with 255 CPUS and everything worked. Currently everything (except module data) we place in the per cpu area we know about at compile time. So instead of allocating a fixed size for the per_cpu area allocate the number of bytes we need plus a fixed constant for to be used for modules. It isn't perfect but it is much less of a pain to work with than what we are doing now. Signed-off-by: Eric W. Biederman --- arch/x86_64/kernel/setup64.c | 7 ++----- include/asm-x86_64/percpu.h | 10 ++++++++++ 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c index 0cd3694..94336cf 100644 --- a/arch/x86_64/kernel/setup64.c +++ b/arch/x86_64/kernel/setup64.c @@ -95,12 +95,9 @@ #ifdef CONFIG_HOTPLUG_CPU #endif /* Copy section for each CPU (we discard the original) */ - size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES); -#ifdef CONFIG_MODULES - if (size < PERCPU_ENOUGH_ROOM) - size = PERCPU_ENOUGH_ROOM; -#endif + size = PERCPU_ENOUGH_ROOM; + printk(KERN_INFO "PERCPU: Allocating %d bytes of per cpu data\n", size); for_each_cpu_mask (i, cpu_possible_map) { char *ptr; diff --git a/include/asm-x86_64/percpu.h b/include/asm-x86_64/percpu.h index 08dd9f9..39d2bab 100644 --- a/include/asm-x86_64/percpu.h +++ b/include/asm-x86_64/percpu.h @@ -11,6 +11,16 @@ #ifdef CONFIG_SMP #include +#ifdef CONFIG_MODULES +# define PERCPU_MODULE_RESERVE 8192 +#else +# define PERCPU_MODULE_RESERVE 0 +#endif + +#define PERCPU_ENOUGH_ROOM \ + (ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) + \ + PERCPU_MODULE_RESERVE) + #define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset) #define __my_cpu_offset() read_pda(data_offset) -- 1.4.2.rc3.g7e18e - 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/