[PATCH 0/3] powerpc: Instrument Hypervisor Calls: add sysfs files
Nathan Lynch
ntl at pobox.com
Thu Jun 15 00:22:23 EST 2006
Hi Mike-
> +#ifdef CONFIG_HCALL_STATS
> +DECLARE_PER_CPU(struct hcall_stats[MAX_HCALL_OPCODES+1], hcall_stats);
> +
> +static ssize_t show_hcall_stats(struct sys_device *dev, char *buf)
> +{
> + struct cpu *cpu = container_of(dev, struct cpu, sysdev);
> + struct hcall_stats *hs = per_cpu(hcall_stats, cpu->sysdev.id);
> + size_t rc = 0;
> + size_t b_written = 0;
> + size_t b_remain = PAGE_SIZE;
> + unsigned long i;
> +
> + for (i=0; i<MAX_HCALL_OPCODES+1; i++){
Coding style:
i < MAX_HCALL_OPCODES + 1
> + if (!hs[i].num_calls)
> + continue;
> +
> + b_written = snprintf(buf+rc, b_remain,
> + "%lu %lu %lu\n",
> + i<<2, hs[i].num_calls, hs[i].total_time);
> +
> + if (b_written >= b_remain)
> + break; /* end of buffer */
> +
> + rc += b_written;
> + b_remain -= b_written;
> + }
> +
> + return rc;
> +}
This flagrantly violates the one-value-per-file rule for sysfs. ;)
Maybe debugfs or some other mechanism would be more appropriate.
Do we not run the risk of having output truncated after the system has
been up for a while and has done a few million hcalls?
> +
> +static SYSDEV_ATTR(hcall_stats, 0666, show_hcall_stats, NULL);
Mode should be 0444 or 0400, no need to have write permissions.
> +#endif /* CONFIG_HCALL_STATS */
> +
> static int __init topology_init(void)
> {
> int cpu;
> @@ -390,6 +423,9 @@ static int __init topology_init(void)
> register_cpu(c, cpu, parent);
>
> sysdev_create_file(&c->sysdev, &attr_physical_id);
> +#ifdef CONFIG_HCALL_STATS
> + sysdev_create_file(&c->sysdev, &attr_hcall_stats);
> +#endif
Let's not create the file on non-lpar systems.
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