Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762597AbXFSSnb (ORCPT ); Tue, 19 Jun 2007 14:43:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762236AbXFSSnP (ORCPT ); Tue, 19 Jun 2007 14:43:15 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:53313 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762221AbXFSSnO (ORCPT ); Tue, 19 Jun 2007 14:43:14 -0400 Date: Tue, 19 Jun 2007 14:42:45 -0400 From: Jeff Dike To: Andrew Morton Cc: LKML , uml-devel Subject: [PATCH 2/2] UML - Add stack usage monitoring Message-ID: <20070619184245.GA10567@c2.user-mode-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3995 Lines: 116 Add a machanism to see how much of a kernel stack is used. This allocates zeroed stacks and sees where the lowest non-zero byte is on process exit. It keeps track of the lowest value and logs values as they get lower. Signed-off-by: Jeff Dike -- arch/um/Kconfig.debug | 9 +++++++++ arch/um/defconfig | 1 + arch/um/kernel/process.c | 29 +++++++++++++++++++++++++++++ include/asm-um/thread_info.h | 16 ++++++++++++++++ 4 files changed, 55 insertions(+) Index: linux-2.6.21-mm/arch/um/Kconfig.debug =================================================================== --- linux-2.6.21-mm.orig/arch/um/Kconfig.debug 2007-06-19 13:37:16.000000000 -0400 +++ linux-2.6.21-mm/arch/um/Kconfig.debug 2007-06-19 14:05:59.000000000 -0400 @@ -47,4 +47,13 @@ config GCOV If you're involved in UML kernel development and want to use gcov, say Y. If you're unsure, say N. +config DEBUG_STACK_USAGE + bool "Stack utilization instrumentation" + 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. + + This option will slow down process creation and destruction somewhat. endmenu Index: linux-2.6.21-mm/arch/um/kernel/process.c =================================================================== --- linux-2.6.21-mm.orig/arch/um/kernel/process.c 2007-06-19 13:37:16.000000000 -0400 +++ linux-2.6.21-mm/arch/um/kernel/process.c 2007-06-19 14:01:55.000000000 -0400 @@ -411,3 +411,32 @@ unsigned long arch_align_stack(unsigned return sp & ~0xf; } #endif + +#ifdef CONFIG_DEBUG_STACK_USAGE + +static DEFINE_SPINLOCK(low_water_lock); +static int lowest_to_date = THREAD_SIZE; + +void check_stack_usage(struct thread_info *s) +{ + unsigned int *stack, *p, *end; + int left; + + stack = (unsigned int *) (s + 1); + end = (unsigned int *) ((unsigned long) s + THREAD_SIZE); + for(p = stack; p < end; p++){ + if(*p != 0) + break; + } + + left = (p - stack) * sizeof(*p); + + spin_lock(&low_water_lock); + if(left < lowest_to_date){ + printk("Greatest stack depth - %d bytes left\n", left); + lowest_to_date = left; + } + spin_unlock(&low_water_lock); +} + +#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 2007-06-19 13:37:16.000000000 -0400 +++ linux-2.6.21-mm/include/asm-um/thread_info.h 2007-06-19 13:57:07.000000000 -0400 @@ -52,6 +52,20 @@ static inline struct thread_info *curren return ti; } +#ifdef CONFIG_DEBUG_STACK_USAGE + +extern void check_stack_usage(struct thread_info *stack); + +#define alloc_thread_info(tsk) \ + ((struct thread_info *) __get_free_pages(GFP_KERNEL | __GFP_ZERO, \ + CONFIG_KERNEL_STACK_ORDER)) + +#define free_thread_info(ti) ({ check_stack_usage(ti) ; \ + free_pages((unsigned long)(ti), \ + CONFIG_KERNEL_STACK_ORDER); }) + +#else + /* thread information allocation */ #define alloc_thread_info(tsk) \ ((struct thread_info *) __get_free_pages(GFP_KERNEL, \ @@ -61,6 +75,8 @@ 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 2007-06-19 13:37:16.000000000 -0400 +++ linux-2.6.21-mm/arch/um/defconfig 2007-06-19 13:51:44.000000000 -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_DEBUG_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/