Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757585AbXEIUcr (ORCPT ); Wed, 9 May 2007 16:32:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754642AbXEIUck (ORCPT ); Wed, 9 May 2007 16:32:40 -0400 Received: from [198.99.130.12] ([198.99.130.12]:40412 "EHLO saraswathi.solana.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753996AbXEIUcj (ORCPT ); Wed, 9 May 2007 16:32:39 -0400 Date: Wed, 9 May 2007 16:27:22 -0400 From: Jeff Dike To: Andrew Morton Cc: LKML , uml-devel Subject: [PATCH 5/6] UML - Monitor stack usage Message-ID: <20070509202722.GA22464@c2.user-mode-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4135 Lines: 125 In preparation for reducing stack size, add a machanism to see how much of a kernel stack is used. This fills a new stack with 0x6b on allocation and sees where the lowest non-0x6b byte is on process exit. It keeps track of the lowest value and logs values as they get lower. The lowest values I've seen so far are ~1250 bytes remaining on i386 (with order 0 stacks) and ~2650 on x86_64 (order 1). Signed-off-by: Jeff Dike -- arch/um/Kconfig.debug | 8 ++++++++ arch/um/defconfig | 1 + arch/um/kernel/process.c | 35 +++++++++++++++++++++++++++++++++++ include/asm-um/thread_info.h | 16 ++++++++++++++++ 4 files changed, 60 insertions(+) Index: linux-2.6.21-mm/arch/um/Kconfig.debug =================================================================== --- linux-2.6.21-mm.orig/arch/um/Kconfig.debug 2007-05-09 14:34:39.000000000 -0400 +++ linux-2.6.21-mm/arch/um/Kconfig.debug 2007-05-09 14:36:10.000000000 -0400 @@ -47,4 +47,12 @@ config GCOV If you're involved in UML kernel development and want to use gcov, say Y. If you're unsure, say N. +config STACK_USAGE + bool "Track kernel stack usage" + default N + help + Track the maximum kernel stack usage - this will look at each + kernel stack at process exit and log it if it's the deepest + stack seen so far. + endmenu Index: linux-2.6.21-mm/arch/um/kernel/process.c =================================================================== --- linux-2.6.21-mm.orig/arch/um/kernel/process.c 2007-05-09 14:34:39.000000000 -0400 +++ linux-2.6.21-mm/arch/um/kernel/process.c 2007-05-09 14:36:10.000000000 -0400 @@ -427,3 +427,38 @@ unsigned long arch_align_stack(unsigned return sp & ~0xf; } #endif + +#ifdef CONFIG_STACK_USAGE + +static int lowest_to_date = THREAD_SIZE; + +void mark_stack(struct thread_info *stack) +{ + if(stack == NULL) + return; + + memset(stack, 0x6b, THREAD_SIZE); +} + +void check_stack_usage(struct thread_info *s) +{ + unsigned int *stack; + unsigned int *p, *end; + int left; + + stack = (unsigned int *) (s + 1); + end = (unsigned int *) ((unsigned long) stack + THREAD_SIZE); + for(p = stack; p < end; p++){ + if(*p != 0x6b6b6b6b){ + left = (p - stack); + if(left < lowest_to_date){ + printk("Greatest stack depth - %d bytes left\n", + left * sizeof(*p)); + lowest_to_date = left; + } + return; + } + } +} + +#endif Index: linux-2.6.21-mm/include/asm-um/thread_info.h =================================================================== --- linux-2.6.21-mm.orig/include/asm-um/thread_info.h 2007-05-09 14:34:39.000000000 -0400 +++ linux-2.6.21-mm/include/asm-um/thread_info.h 2007-05-09 14:36:10.000000000 -0400 @@ -52,6 +52,20 @@ static inline struct thread_info *curren return ti; } +#ifdef CONFIG_STACK_USAGE + +extern void mark_stack(struct thread_info *stack); +extern void check_stack_usage(struct thread_info *stack); + +#define alloc_thread_info(tsk) \ + ({ struct thread_info *stack = kmalloc(THREAD_SIZE, GFP_KERNEL); \ + mark_stack(stack); \ + stack; \ + }) +#define free_thread_info(ti) ({ check_stack_usage(ti) ; kfree(ti); }) + +#else + /* thread information allocation */ #define alloc_thread_info(tsk) \ ((struct thread_info *) kmalloc(THREAD_SIZE, GFP_KERNEL)) @@ -59,6 +73,8 @@ static inline struct thread_info *curren #endif +#endif + #define PREEMPT_ACTIVE 0x10000000 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ Index: linux-2.6.21-mm/arch/um/defconfig =================================================================== --- linux-2.6.21-mm.orig/arch/um/defconfig 2007-05-09 14:42:04.000000000 -0400 +++ linux-2.6.21-mm/arch/um/defconfig 2007-05-09 14:42:59.000000000 -0400 @@ -527,3 +527,4 @@ CONFIG_FORCED_INLINING=y # CONFIG_RCU_TORTURE_TEST is not set # CONFIG_GPROF is not set # CONFIG_GCOV is not set +# CONFIG_STACK_USAGE is not set - 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/