Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765232AbXFSTuy (ORCPT ); Tue, 19 Jun 2007 15:50:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760694AbXFSTup (ORCPT ); Tue, 19 Jun 2007 15:50:45 -0400 Received: from [198.99.130.12] ([198.99.130.12]:53579 "EHLO saraswathi.solana.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1760518AbXFSTuo (ORCPT ); Tue, 19 Jun 2007 15:50:44 -0400 Date: Tue, 19 Jun 2007 15:50:03 -0400 From: Jeff Dike To: Andrew Morton Cc: LKML , uml-devel Subject: Re: [PATCH 2/2] UML - Add stack usage monitoring Message-ID: <20070619195003.GA11718@c2.user-mode-linux.org> References: <20070619184245.GA10567@c2.user-mode-linux.org> <20070619115422.de61abd5.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070619115422.de61abd5.akpm@linux-foundation.org> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4982 Lines: 148 On Tue, Jun 19, 2007 at 11:54:22AM -0700, Andrew Morton wrote: > On Tue, 19 Jun 2007 14:42:45 -0400 > Jeff Dike wrote: > > > 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. > > > > remind us again why the generic code is unsuitable? It does something different - it will tell you the greatest stack usage of any currently running process. What I want to be able to do is run a workload and come back a few days later and see how close anything came to running out of stack. > > > + for(p = stack; p < end; p++){ > > + if(*p != 0) > > + if(left < lowest_to_date){ > > Are there any plans to fix UML coding style? You know I have been fixing it. I forgot to eyeball this patch for style - fixed patch below. Jeff -- Work email - jdike at linux dot intel dot com 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 14:06:36.000000000 -0400 +++ linux-2.6.21-mm/arch/um/Kconfig.debug 2007-06-19 14:06:44.000000000 -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 14:06:36.000000000 -0400 +++ linux-2.6.21-mm/arch/um/kernel/process.c 2007-06-19 15:48:20.000000000 -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 14:06:36.000000000 -0400 +++ linux-2.6.21-mm/include/asm-um/thread_info.h 2007-06-19 14:06:44.000000000 -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 14:06:36.000000000 -0400 +++ linux-2.6.21-mm/arch/um/defconfig 2007-06-19 14:06:44.000000000 -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/