lkml.org 
[lkml]   [2016]   [Oct]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 11/18] x86/intel_rdt: Add basic resctrl filesystem support
On Fri, 14 Oct 2016, Fenghua Yu wrote:
> +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> + *
> + * More information about RDT be found in the Intel (R) x86 Architecture
> + * Software Developer Manual.

Yes, that's how it should look like.

> +static void l3_qos_cfg_update(void *arg)
> +{
> + struct rdt_resource *r = arg;
> +
> + wrmsrl(IA32_L3_QOS_CFG, r->cdp_enabled);
> +}
> +
> +static void set_l3_qos_cfg(struct rdt_resource *r)
> +{
> + struct list_head *l;
> + struct rdt_domain *d;
> + struct cpumask cpu_mask;

You cannot have cpumasks on stack.

cpumask_var_t mask;

if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
return -ENOMEM;


> + int cpu;
> +
> + cpumask_clear(&cpu_mask);

That can go away then

> + list_for_each(l, &r->domains) {

list_for_each_entry() again

> + d = list_entry(l, struct rdt_domain, list);
> + cpumask_set_cpu(cpumask_any(&d->cpu_mask), &cpu_mask);

A comment to explain what this does would be helpful.

> + }
> + cpu = get_cpu();
> + /* Update QOS_CFG MSR on this cpu if it's in cpu_mask. */
> + if (cpumask_test_cpu(cpu, &cpu_mask))
> + l3_qos_cfg_update(r);
> + /* Update QOS_CFG MSR on all other cpus in cpu_mask. */
> + smp_call_function_many(&cpu_mask, l3_qos_cfg_update, r, 1);
> + put_cpu();
> +}
> +
> +static int parse_rdtgroupfs_options(char *data)
> +{
> + char *token, *o = data;
> + struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3];
> +
> + r->cdp_enabled = false;
> + while ((token = strsep(&o, ",")) != NULL) {
> + if (!*token)
> + return -EINVAL;
> +
> + if (!strcmp(token, "cdp"))
> + if (r->enabled && r->cdp_capable)
> + r->cdp_enabled = true;
> + }
> +
> + return 0;
> +}
> +
> +static struct dentry *rdt_mount(struct file_system_type *fs_type,
> + int flags, const char *unused_dev_name,
> + void *data)
> +{
> + struct dentry *dentry;
> + int ret;
> + bool new_sb;
> +
> + mutex_lock(&rdtgroup_mutex);
> + /*
> + * resctrl file system can only be mounted once.
> + */
> + if (static_branch_unlikely(&rdt_enable_key)) {
> + dentry = ERR_PTR(-EBUSY);
> + goto out;
> + }
> +
> + ret = parse_rdtgroupfs_options(data);
> + if (ret) {
> + dentry = ERR_PTR(ret);
> + goto out;
> + }
> +
> + dentry = kernfs_mount(fs_type, flags, rdt_root,
> + RDTGROUP_SUPER_MAGIC, &new_sb);

&new_sb is pointless here. It just tells the caller that a new superblock
has been created, So in case of a valid dentry new_sb will always be true,
and if anything failed in kernfs_mount() including the allocation of a new
superblock then new_sb is completely irrelevant as IS_ERR(dentry) will be
true. So you can just hand in NULL because you do not allow multiple
mounts.

> + if (IS_ERR(dentry))
> + goto out;
> + if (!new_sb) {
> + dentry = ERR_PTR(-EINVAL);
> + goto out;
> + }
> + if (rdt_resources_all[RDT_RESOURCE_L3].cdp_capable)
> + set_l3_qos_cfg(&rdt_resources_all[RDT_RESOURCE_L3]);
> + static_branch_enable(&rdt_enable_key);
> +
> +out:
> + mutex_unlock(&rdtgroup_mutex);
> +
> + return dentry;
> +}
> +
> +static void reset_all_cbms(struct rdt_resource *r)
> +{
> + struct list_head *l;
> + struct rdt_domain *d;
> + struct msr_param msr_param;
> + struct cpumask cpu_mask;
> + int i, cpu;
> +
> + cpumask_clear(&cpu_mask);
> + msr_param.res = r;
> + msr_param.low = 0;
> + msr_param.high = r->max_closid;
> +
> + list_for_each(l, &r->domains) {
> + d = list_entry(l, struct rdt_domain, list);

list_for_each_entry()

> + cpumask_set_cpu(cpumask_any(&d->cpu_mask), &cpu_mask);
> +
> + for (i = 0; i < r->max_closid; i++)
> + d->cbm[i] = r->max_cbm;
> + }
> + cpu = get_cpu();
> + /* Update CBM on this cpu if it's in cpu_mask. */
> + if (cpumask_test_cpu(cpu, &cpu_mask))
> + rdt_cbm_update(&msr_param);
> + /* Updte CBM on all other cpus in cpu_mask. */

Update

> + smp_call_function_many(&cpu_mask, rdt_cbm_update, &msr_param, 1);
> + put_cpu();
> +}
> +

Thanks,

tglx

\
 
 \ /
  Last update: 2016-10-17 21:38    [W:0.192 / U:15.952 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site