Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932496AbXK2R7Q (ORCPT ); Thu, 29 Nov 2007 12:59:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759302AbXK2R66 (ORCPT ); Thu, 29 Nov 2007 12:58:58 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:36383 "EHLO dorka.pomaz.szeredi.hu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756750AbXK2R65 (ORCPT ); Thu, 29 Nov 2007 12:58:57 -0500 To: mingo@elte.hu CC: jdike@addtoit.com, user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org In-reply-to: <20071129171647.GA1326@elte.hu> (message from Ingo Molnar on Thu, 29 Nov 2007 18:16:47 +0100) Subject: Re: scheduling anomaly on uml (was: -rt doesn't compile for UML) References: <20071128150637.GA5518@c2.user-mode-linux.org> <20071128182935.GA8048@c2.user-mode-linux.org>

<20071129170205.GA7415@c2.user-mode-linux.org> <20071129171647.GA1326@elte.hu> Message-Id: From: Miklos Szeredi Date: Thu, 29 Nov 2007 18:58:41 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5060 Lines: 156 > > On Thu, Nov 29, 2007 at 11:19:40AM +0100, Miklos Szeredi wrote: > > > date-7119 0.... 15636591us!: schedule (0 0) > > > bash-502 0.... 15643908us!: schedule (0 0) > > > bash-502 0.... 15646250us!: schedule (0 0) > > > > How exactly did you end up getting this data? This: http://people.redhat.com/mingo/latency-tracing-patches/tracing-QuickStart.txt and some hacking, which is probably not very useful: Index: linux/include/asm-um/rtc.h =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux/include/asm-um/rtc.h 2007-11-28 17:41:42.000000000 +0100 @@ -0,0 +1 @@ +/* stub for the latency tracer */ Index: linux/include/asm-um/irqflags.h =================================================================== --- linux.orig/include/asm-um/irqflags.h 2007-11-28 17:36:21.000000000 +0100 +++ linux/include/asm-um/irqflags.h 2007-11-28 17:41:42.000000000 +0100 @@ -1,6 +1,9 @@ #ifndef __UM_IRQFLAGS_H #define __UM_IRQFLAGS_H -/* Empty for now */ +static inline int raw_irqs_disabled_flags(unsigned long flags) +{ + return 0; +} #endif Index: linux/kernel/latency_trace.c =================================================================== --- linux.orig/kernel/latency_trace.c 2007-11-28 17:41:35.000000000 +0100 +++ linux/kernel/latency_trace.c 2007-11-29 16:05:45.000000000 +0100 @@ -26,6 +26,7 @@ #include #include #include +#include #include #ifndef DEFINE_RAW_SPINLOCK @@ -59,6 +60,8 @@ static unsigned long notrace cycles_to_u delta = mulhwu(tb_to_us, delta); #elif defined(CONFIG_ARM) delta = mach_cycles_to_usecs(delta); +#elif defined(CONFIG_UML) + /* Dunno */ #else #error Implement cycles_to_usecs. #endif @@ -188,7 +191,7 @@ static int report_latency(cycle_t delta) /* * Number of per-CPU trace entries: */ -#define MAX_TRACE (65536UL*16UL) +#define MAX_TRACE (1024UL*16UL) #define CMDLINE_BYTES 16 @@ -655,7 +658,7 @@ again: entry->cpu = cpu; #endif entry->flags = (irqs_off() ? TRACE_FLAG_IRQS_OFF : 0) | - (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_HARD_OFF : 0)| + (raw_irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_HARD_OFF : 0)| ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) | ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) | (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) | @@ -2709,7 +2712,7 @@ void __init init_tracer(void) for_each_possible_cpu(cpu) { tr = cpu_traces + cpu; - array = tracer_alloc_bootmem(size); + array = alloc_bootmem(size); if (!array) { printk(KERN_ERR "CPU#%d: failed to allocate %ld bytes trace buffer!\n", @@ -2723,7 +2726,7 @@ void __init init_tracer(void) tr->cpu = cpu; tr->trace = array; - array = tracer_alloc_bootmem(size); + array = alloc_bootmem(size); if (!array) { printk(KERN_ERR "CPU#%d: failed to allocate %ld bytes max-trace buffer!\n", @@ -2742,7 +2745,7 @@ void __init init_tracer(void) * trace entries for the first cpu-trace structure: */ size = sizeof(struct trace_entry)*MAX_TRACE*num_possible_cpus(); - array = tracer_alloc_bootmem(size); + array = alloc_bootmem(size); if (!array) { printk(KERN_ERR "failed to allocate %ld bytes out-trace buffer!\n", Index: linux/arch/um/sys-i386/sysrq.c =================================================================== --- linux.orig/arch/um/sys-i386/sysrq.c 2007-10-09 22:31:38.000000000 +0200 +++ linux/arch/um/sys-i386/sysrq.c 2007-11-29 16:20:12.000000000 +0100 @@ -7,6 +7,7 @@ #include "linux/smp.h" #include "linux/sched.h" #include "linux/kallsyms.h" +#include "linux/stacktrace.h" #include "asm/ptrace.h" #include "sysrq.h" @@ -99,3 +100,26 @@ void show_trace(struct task_struct* task printk("\n"); } +void save_stack_trace(struct stack_trace *trace) +{ + unsigned long ebp; + struct thread_info *tinfo; + unsigned long stack; + unsigned long addr; + + asm ("movl %%ebp, %0" : "=r" (ebp) : ); + + tinfo = (struct thread_info *) + ((unsigned long)(&stack) & (~(THREAD_SIZE - 1))); + + while (valid_stack_ptr(tinfo, (void *)ebp)) { + addr = *(unsigned long *)(ebp + 4); + if (trace->skip > 0) { + trace->skip--; + } else if (trace->nr_entries < trace->max_entries) { + trace->entries[trace->nr_entries++] = addr; + } + ebp = *(unsigned long *)ebp; + } +} + Index: linux/kernel/sched.c =================================================================== --- linux.orig/kernel/sched.c 2007-11-29 16:29:08.000000000 +0100 +++ linux/kernel/sched.c 2007-11-29 16:29:20.000000000 +0100 @@ -3658,6 +3658,7 @@ need_resched_nonpreemptible: next = pick_next_task(rq, prev); trace_all_runnable_tasks(rq); + trace_special_sym(); sched_info_switch(prev, next); - 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/