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Message-Id: <20080904190308.6d377ac6.randy.dunlap@oracle.com>
Date: Thu, 4 Sep 2008 19:03:08 -0700
From: Randy Dunlap <randy.dunlap@...cle.com>
To: Dave Hansen <dave@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] dynamically enable readprofile at runtime
On Fri, 29 Aug 2008 13:27:13 -0700 Dave Hansen wrote:
> Way too often, I have a machine that exhibits some kind of crappy
> behavior. The CPU looks wedged in the kernel or it is spending
> way too much system time and I wonder what is responsible.
>
> I try to run readprofile. But, of course, Ubuntu doesn't enable
> it by default. Dang!
>
> The reason we boot-time enable it is that it takes a big bufffer
> that we generally can only bootmem alloc. But, does it hurt to
> at least try and runtime-alloc it?
>
> To use:
> echo 2 > /sys/kernel/profile
>
> Then run readprofile like normal.
I like it.
> Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com>
> ---
>
> linux-2.6.git-dave/kernel/ksysfs.c | 29 +++++++++++++++++++++++++++++
> linux-2.6.git-dave/kernel/profile.c | 33 ++++++++++++++++++++++++---------
> 2 files changed, 53 insertions(+), 9 deletions(-)
>
> diff -puN kernel/ksysfs.c~dynamic-readprofile kernel/ksysfs.c
> --- linux-2.6.git/kernel/ksysfs.c~dynamic-readprofile 2008-08-29 13:15:52.000000000 -0700
> +++ linux-2.6.git-dave/kernel/ksysfs.c 2008-08-29 13:19:03.000000000 -0700
> @@ -14,6 +14,7 @@
> #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/kexec.h>
> +#include <linux/profile.h>
> #include <linux/sched.h>
>
> #define KERNEL_ATTR_RO(_name) \
> @@ -53,6 +54,31 @@ static ssize_t uevent_helper_store(struc
> KERNEL_ATTR_RW(uevent_helper);
> #endif
>
> +#ifdef CONFIG_PROFILING
> +/* uevent helper program, used during early boo */
s/boo/boot/ ??
> +static ssize_t profiling_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", prof_on);
> +}
> +static ssize_t profiling_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int ret;
> +
> + profile_setup(buf);
> + profile_init();
> + if (!prof_buffer)
> + return -ENOMEM;
> + ret = create_proc_profile();
> + if (ret)
> + return ret;
> + return count;
> +}
> +KERNEL_ATTR_RW(profiling);
> +#endif
> +
> #ifdef CONFIG_KEXEC
> static ssize_t kexec_loaded_show(struct kobject *kobj,
> struct kobj_attribute *attr, char *buf)
> @@ -109,6 +135,9 @@ static struct attribute * kernel_attrs[]
> &uevent_seqnum_attr.attr,
> &uevent_helper_attr.attr,
> #endif
> +#ifdef CONFIG_PROFILING
> + &profiling_attr.attr,
> +#endif
> #ifdef CONFIG_KEXEC
> &kexec_loaded_attr.attr,
> &kexec_crash_loaded_attr.attr,
> diff -puN kernel/profile.c~dynamic-readprofile kernel/profile.c
> --- linux-2.6.git/kernel/profile.c~dynamic-readprofile 2008-08-29 13:15:52.000000000 -0700
> +++ linux-2.6.git-dave/kernel/profile.c 2008-08-29 13:18:50.000000000 -0700
> @@ -50,11 +50,11 @@ static DEFINE_PER_CPU(int, cpu_profile_f
> static DEFINE_MUTEX(profile_flip_mutex);
> #endif /* CONFIG_SMP */
>
> -static int __init profile_setup(char *str)
> +int profile_setup(char *str)
> {
> - static char __initdata schedstr[] = "schedule";
> - static char __initdata sleepstr[] = "sleep";
> - static char __initdata kvmstr[] = "kvm";
> + static char schedstr[] = "schedule";
> + static char sleepstr[] = "sleep";
> + static char kvmstr[] = "kvm";
> int par;
>
> if (!strncmp(str, sleepstr, strlen(sleepstr))) {
> @@ -100,14 +100,29 @@ static int __init profile_setup(char *st
> __setup("profile=", profile_setup);
>
>
> -void __init profile_init(void)
> +void profile_init(void)
> {
> + int buffer_bytes;
> if (!prof_on)
> return;
>
> /* only text is profiled */
> prof_len = (_etext - _stext) >> prof_shift;
> - prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t));
> + buffer_bytes = prof_len*sizeof(atomic_t);
> + if (!slab_is_available()) {
> + prof_buffer = alloc_bootmem(buffer_bytes);
> + return;
> + }
> +
> + prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL);
> + if (prof_buffer)
> + return;
> +
> + prof_buffer = alloc_pages_exact(buffer_bytes, GFP_KERNEL|__GFP_ZERO);
> + if (prof_buffer)
> + return;
> +
> + prof_buffer = vmalloc(buffer_bytes);
> }
>
> /* Profile event notifications */
> @@ -527,7 +542,7 @@ static void __init profile_nop(void *unu
> {
> }
>
> -static int __init create_hash_tables(void)
> +static int create_hash_tables(void)
> {
> int cpu;
>
> @@ -575,14 +590,14 @@ out_cleanup:
> #define create_hash_tables() ({ 0; })
> #endif
>
> -static int __init create_proc_profile(void)
> +int create_proc_profile(void)
> {
> struct proc_dir_entry *entry;
>
> if (!prof_on)
> return 0;
> if (create_hash_tables())
> - return -1;
> + return -ENOMEM;
> entry = proc_create("profile", S_IWUSR | S_IRUGO,
> NULL, &proc_profile_operations);
> if (!entry)
---
~Randy
Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA
http://linuxplumbersconf.org/
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