On Wed, 23 Aug 2006 01:05:56 -0700
Stephane Eranian <[email protected]> wrote:
> This patch contains the sysfs support.
>
> We use the sysfs interface fot two reasons:
> - perfmon2 administration
> - user level information
>
> Perfmon2 creates new directories in /sys:
> - /sys/kernel/perfmon: for adminstration and global information
> - /sys/devices/system/cpu/cpuXX/perfmon: per-cpu statistics (debugging)
>
> In /sys/kernel/perfmon we find:
> - arg_size_max (R/W): maximum size of vector arguments in bytes
> - buf_size_max (R/W): maximum aggregated size of all smapling buffers
> - smpl_buffer_mem (R): current consumption of buf_size_max
> - counter_width (R): PMU HW counter width
> - debug (R/W) : enable perfmon2 debugging messages
> - debug_ovfl (R/W): enable perfmon2 interrupt debugging messages
> - formats/ : information about available sampling formats
> - pmc_max_fast_arg (R): how many vector arguments can be processed on the stack for pfarg_pmc_t
> - pmd_max_fast_arg (R): how many vector arguments can be processed on the stack for pfarg_pmd_t
> - pmu_desc/ : information about PMU register mapping
> - pmu_model (R): name of active PMU description module
> - reset_stats (W): reset statistics
> - sys_group (R/W): which user group is allowed to create systemwide perfmon2 contexts
> - task_group (R/W): which user group is allowed to create per-thread perfmon2 contexts
> - sys_sessions_count (R): number of active per-thread contexts
> - task_sessions_count (R): number of active system-wide contexts
> - version (R): perfmon2 version
>
> The statistics we maintained in /sys/system/devices/cpu/cpuXX are mostly
> for debugging purposes at this point.
>
>
>
>
> --- linux-2.6.17.9.base/perfmon/perfmon_sysfs.c 1969-12-31 16:00:00.000000000 -0800
> +++ linux-2.6.17.9/perfmon/perfmon_sysfs.c 2006-08-21 03:37:46.000000000 -0700
> @@ -0,0 +1,637 @@
> +/*
> + * perfmon_proc.c: perfmon2 /proc interface
> + *
> + * This file implements the perfmon2 interface which
> + * provides access to the hardware performance counters
> + * of the host processor.
> + *
> + * The initial version of perfmon.c was written by
> + * Ganesh Venkitachalam, IBM Corp.
> + *
> + * Then it was modified for perfmon-1.x by Stephane Eranian and
> + * David Mosberger, Hewlett Packard Co.
> + *
> + * Version Perfmon-2.x is a complete rewrite of perfmon-1.x
> + * by Stephane Eranian, Hewlett Packard Co.
> + *
> + * Copyright (c) 1999-2006 Hewlett-Packard Development Company, L.P.
> + * Contributed by Stephane Eranian <[email protected]>
> + * David Mosberger-Tang <[email protected]>
> + *
> + * More information about perfmon available at:
> + * http://www.hpl.hp.com/research/linux/perfmon
> + */
> +#include <linux/config.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/smp_lock.h>
> +#include <linux/proc_fs.h>
> +#include <linux/list.h>
> +#include <linux/version.h>
> +#include <linux/perfmon.h>
> +#include <linux/device.h>
> +#include <linux/cpu.h>
> +
> +#include <asm/bitops.h>
> +#include <asm/errno.h>
> +#include <asm/processor.h>
> +
> +struct pfm_attribute {
> + struct attribute attr;
> + ssize_t (*show)(void *, char *);
> + ssize_t (*store)(void *, const char *, size_t);
> +};
> +#define to_attr(n) container_of(n, struct pfm_attribute, attr);
> +
> +#define PFM_RO_ATTR(_name) \
> +struct pfm_attribute attr_##_name = __ATTR_RO(_name)
> +
> +#define PFM_RW_ATTR(_name,_mode,_show,_store) \
> +struct pfm_attribute attr_##_name = __ATTR(_name,_mode,_show,_store);
> +
> +static int pfm_sysfs_init_done; /* true when pfm_sysfs_init() completed */
> +
> +static void pfm_sysfs_init_percpu(int i);
>
> +int pfm_sysfs_add_pmu(struct _pfm_pmu_config *pmu);
This is effectively an extern-decl-in-a-C-file. Either it should be
static, or this declaration should be moved to a shared header file.
> +static ssize_t debug_store(void *info, const char *buf, size_t sz)
> +{
> + int d;
> +
> + if (sscanf(buf,"%d", &d) != 1)
> + return -EINVAL;
> +
> + pfm_controls.debug = d;
> +
> + if (d == 0)
> + pfm_reset_stats();
> + return strnlen(buf, PAGE_SIZE);
> +}
hm. Does the sysfs core zero-terminate the incoming buffer? iirc it does.
perhaps a `return sz;' would be simpler and sufficient here.
> +int pfm_sysfs_init(void)
> +{
> + int i, ret;
> +
> + ret = subsystem_register(&pfm_fmt_subsys);
> + if (ret) {
> + PFM_INFO("cannot register pfm_fmt_subsys: %d", ret);
> + return ret;
> + }
> +
> + ret = subsystem_register(&pfm_pmu_subsys);
> + if (ret) {
> + PFM_INFO("cannot register pfm_pmu_subsys: %d", ret);
> + subsystem_unregister(&pfm_fmt_subsys);
> + return ret;
> + }
> +
> + ret = subsystem_register(&pfm_stats_subsys);
> + if (ret) {
> + PFM_INFO("cannot register pfm_statssubsys: %d", ret);
> + subsystem_unregister(&pfm_fmt_subsys);
> + subsystem_unregister(&pfm_pmu_subsys);
> + return ret;
> + }
We prefer the `goto out;' version of error recovery.
> + kobject_init(&pfm_kernel_kobj);
> + kobject_init(&pfm_kernel_fmt_kobj);
> +
> + pfm_kernel_kobj.parent = &kernel_subsys.kset.kobj;
> + kobject_set_name(&pfm_kernel_kobj, "perfmon");
> +
> + pfm_kernel_fmt_kobj.parent = &pfm_kernel_kobj;
> + kobject_set_name(&pfm_kernel_fmt_kobj, "formats");
> +
> + kobject_add(&pfm_kernel_kobj);
> + kobject_add(&pfm_kernel_fmt_kobj);
> +
> + sysfs_create_group(&pfm_kernel_kobj, &pfm_kernel_attr_group);
> +
> + for_each_online_cpu(i) {
> + pfm_sysfs_init_percpu(i);
> + }
Does this code support CPU hotplug?
> + pfm_sysfs_init_done = 1;
> +
> + pfm_builtin_fmt_sysfs_add();
> +
> + if (pfm_pmu_conf)
> + pfm_sysfs_add_pmu(pfm_pmu_conf);
> +
> + return 0;
> +}
> +
>
> ...
>
> +
> +static ssize_t uuid_show(void *data, char *buf)
> +{
> + struct pfm_smpl_fmt *fmt = data;
> +
> + return snprintf(buf, PAGE_SIZE, "%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x"
> + "-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x\n",
> + fmt->fmt_uuid[0],
> + fmt->fmt_uuid[1],
> + fmt->fmt_uuid[2],
> + fmt->fmt_uuid[3],
> + fmt->fmt_uuid[4],
> + fmt->fmt_uuid[5],
> + fmt->fmt_uuid[6],
> + fmt->fmt_uuid[7],
> + fmt->fmt_uuid[8],
> + fmt->fmt_uuid[9],
> + fmt->fmt_uuid[10],
> + fmt->fmt_uuid[11],
> + fmt->fmt_uuid[12],
> + fmt->fmt_uuid[13],
> + fmt->fmt_uuid[14],
> + fmt->fmt_uuid[15]);
> +}
Why does perfmon play with UUIDs??
> +
> +int pfm_sysfs_add_fmt(struct pfm_smpl_fmt *fmt)
> +{
> + int ret;
> +
> + if (pfm_sysfs_init_done == 0)
> + return 0;
> +
> + kobject_init(&fmt->kobj);
> + kobject_set_name(&fmt->kobj, fmt->fmt_name);
> + kobj_set_kset_s(fmt, pfm_fmt_subsys);
> + fmt->kobj.parent = &pfm_kernel_fmt_kobj;
> +
> + ret = kobject_add(&fmt->kobj);
> +
> + return sysfs_create_file(&fmt->kobj, &attr_uuid.attr);
> +}
> +
> +int pfm_sysfs_remove_fmt(struct pfm_smpl_fmt *fmt)
> +{
> + if (pfm_sysfs_init_done == 0)
> + return 0;
> +
> + sysfs_remove_file(&fmt->kobj, &attr_uuid.attr);
> +
> + kobject_del(&fmt->kobj);
> +
> + return 0;
> +}
What do these do? (Some comments would be nice)
> +/*
> + * because the mappings can vary between one PMU and the other, we cannot really
> + * use an attribute per PMC to describe a mapping. Instead we have a single
> + * mappings attribute per PMU.
> + */
> +static ssize_t mappings_show(void *data, char *buf)
> +{
> + struct _pfm_pmu_config *pmu = data;
> + size_t s = PAGE_SIZE;
> + u32 n = 0, i;
> +
> + for (i = 0; i < PFM_MAX_PMCS; i++) {
> +
> + if ((pmu->pmc_desc[i].type & PFM_REG_I) == 0)
> + continue;
> +
> + n = snprintf(buf, s, "PMC%u:0x%llx:0x%llx:%s\n",
> + i,
> + (unsigned long long)pfm_pmu_conf->pmc_desc[i].dfl_val,
> + (unsigned long long)pfm_pmu_conf->pmc_desc[i].rsvd_msk,
> + pfm_pmu_conf->pmc_desc[i].desc);
> + buf += n;
> + if (n > s)
> + goto skip;
> + s -= n;
> + }
> +
> + for (i = 0; i < PFM_MAX_PMDS; i++) {
> +
> + if ((pmu->pmd_desc[i].type & PFM_REG_I) == 0)
> + continue;
> +
> + n = snprintf(buf, s, "PMD%u:0x%llx:0x%llx:%s\n",
> + i,
> + (unsigned long long)pfm_pmu_conf->pmd_desc[i].dfl_val,
> + (unsigned long long)pfm_pmu_conf->pmd_desc[i].rsvd_msk,
> + pfm_pmu_conf->pmd_desc[i].desc);
> + buf += n;
> + if (n > s)
> + break;
> + s -= n;
> + }
> +skip:
> + return PAGE_SIZE - s;
> +}
This breaks the one-value-per-sysfs-file rule.
> +PFM_RO_ATTR(mappings);
> +
> +int pfm_sysfs_add_pmu(struct _pfm_pmu_config *pmu)
> +{
> + if (pfm_sysfs_init_done == 0)
> + return 0;
> +
> + kobject_init(&pmu->kobj);
> + kobject_set_name(&pmu->kobj, "pmu_desc");
> + kobj_set_kset_s(pmu, pfm_pmu_subsys);
> + pmu->kobj.parent = &pfm_kernel_kobj;
> +
> + kobject_add(&pmu->kobj);
> +
> + return sysfs_create_file(&pmu->kobj, &attr_mappings.attr);
> +}
> +
> +int pfm_sysfs_remove_pmu(struct _pfm_pmu_config *pmu)
> +{
> + if (pfm_sysfs_init_done == 0)
> + return 0;
> +
> + sysfs_remove_file(&pmu->kobj, &attr_mappings.attr);
> +
> + kobject_del(&pmu->kobj);
> +
> + return 0;
> +}
Again - comments, please.
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