Levent Serinol <[email protected]> wrote:
>
> This patch enables controlling kernel profiling through proc/sysctl inferface.
>
> With this patch profiling will be available without rebooting the
> machine (especially for
> production servers) with some drawbacks of vmalloc(tlb). So, bootime
> algorithm part is left unchanged for anyone who wishes to use
> profiling as usual without tlb drawback by rebooting the machine.
> --- include/linux/sysctl.h.org 2005-06-13 16:05:17.000000000 +0300
> +++ include/linux/sysctl.h 2005-06-25 15:05:06.000000000 +0300
Patches should be in `patch -p1' form, please. See
http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt
> +static int prof_on = 0;
> +static int prof_booton = 0;
There's no need to explicitly initialise these.
> +#ifdef CONFIG_SMP
> +static int remove_hash_tables(void)
> +{
> + int cpu;
> +
> + smp_mb();
> + on_each_cpu(profile_nop, NULL, 0, 1);
Why?
> + for_each_online_cpu(cpu) {
> + struct page *page;
> +
> + if (per_cpu(cpu_profile_hits, cpu)[0]) {
> + page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
> + per_cpu(cpu_profile_hits, cpu)[0] = NULL;
> + __free_page(page);
> + }
> + if (per_cpu(cpu_profile_hits, cpu)[1]) {
> + page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
> + per_cpu(cpu_profile_hits, cpu)[1] = NULL;
> + __free_page(page);
> + }
> + }
Can this race against itself? If two cpus run the sysctl at the same time?
We seem to have lock_kernel() coverage. It's be nice to do something
firmer.
> +int profile_sysctl_handler(ctl_table *table, int write,
> + struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
> +{
> + int err;
> + struct proc_dir_entry *entry;
> +
> + if (prof_booton && write) return 0;
> + err=proc_dointvec(table, write, file, buffer, length, ppos);
> + if ((err >= 0) && write) {
> + prof_shift = profile_params[1];
> + switch(profile_params[0])
> + {
> + case 0:
> + if (prof_on) {
Coding style is all over the place here, as well as in most of the rest of
the patch.
if (prof_booton && write)
return 0;
err = proc_dointvec(table, write, file, buffer, length, ppos);
if (err >= 0 && write) {
prof_shift = profile_params[1];
switch (profile_params[0])
{
case 0:
if (prof_on) {
Every line was changed there...
Also, doing multiple returns per function is unpopular, although the
very-early
if (foo)
return <something>;
right at the top of the function is OK. You can use
if (err < 0 || !write)
goto out;
to save a tab stop.
> + }
> + break;
}
break;
> + case SCHED_PROFILING || CPU_PROFILING:
eh? I'm surprised the compiler swallowed that. I guess it's the same as
`case 1:'. Looks like a bug though.
> + if (prof_on) return -1;
> + prof_len = (_etext - _stext) >> prof_shift;
> + prof_buffer = vmalloc(prof_len*sizeof(atomic_t));
> + if (!prof_buffer) return(-ENOMEM);
> + if (create_hash_tables()) {
> + vfree(prof_buffer);
> + return -1;
> + }
> + prof_on = profile_params[0];
> + if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL))) {
> + remove_hash_tables();
> + vfree(prof_buffer);
> + return 0;
> + }
> + entry->proc_fops = &proc_profile_operations;
> + entry->size = (1+prof_len) * sizeof(atomic_t);
> +#ifdef CONFIG_HOTPLUG_CPU
> + register_cpu_notifier(&profile_cpu_notifier);
> +#endif
> + profile_discard_flip_buffers();
> + memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
> + switch(prof_on)
> + {
> + case SCHED_PROFILING:printk(KERN_INFO
> + "kernel schedule profiling enabled (shift: %ld)\n",
> + prof_shift);
> + break;
> + case CPU_PROFILING:printk(KERN_INFO
> + "kernel profiling enabled (shift: %ld)\n",
> + prof_shift);
> + break;
> + }
> + break;
> + }
> + }
> + return 0;
> +}
Documentation/CodingStyle is your friend ;)
> --- kernel/sysctl.c.org 2005-06-13 16:05:23.000000000 +0300
> +++ kernel/sysctl.c 2005-06-26 02:06:23.000000000 +0300
> ...
> +extern int profile_params[];
Try to place this declaration in a header.
What locking protects prof_boot_on()? lock_kernel() won't be sufficient
because we're doing sleeping allocations in here.
I suspect it would be best to whap a semaphore around the whole thing.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
