Re: [PATCH V4 13/38] x86/intel_rdt: Introduce "bit_usage" to display cache allocations details

From: Randy Dunlap
Date: Tue May 22 2018 - 16:10:13 EST


On 05/22/2018 04:29 AM, Reinette Chatre wrote:
> With cache regions now explicitly marked as "shareable" or "exclusive"
> we would like to communicate to the user how portions of the cache
> are used.
>
> Introduce "bit_usage" that indicates for each resource
> how portions of the cache are configured to be used.
>
> To assist the user to distinguish whether the sharing is from software or
> hardware we add the following annotation:
>
> 0 - currently unused
> X - currently available for sharing and used by software and hardware
> H - currently used by hardware only but available for software use
> S - currently used and shareable by software only
> E - currently used exclusively by one resource group
>
> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> ---
> arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 79 ++++++++++++++++++++++++++++++++
> 1 file changed, 79 insertions(+)
>

Hi,

All occurrences of seq_puts(f, one_char_string); should instead be
seq_putc(f, one_char);

Same for patch 14.

> diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> index 5b78b4aa1a50..d0040f83532d 100644
> --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> @@ -714,6 +714,78 @@ static int rdt_shareable_bits_show(struct kernfs_open_file *of,
> return 0;
> }
>
> +/**
> + * rdt_bit_usage_show - Display current usage of resources
> + *
> + * A domain is a shared resource that can now be allocated differently. Here
> + * we display the current regions of the domain as an annotated bitmask.
> + * For each domain of this resource its allocation bitmask
> + * is annotated as below to indicate the current usage of the corresponding bit:
> + * 0 - currently unused
> + * X - currently available for sharing and used by software and hardware
> + * H - currently used by hardware only but available for software use
> + * S - currently used and shareable by software only
> + * E - currently used exclusively by one resource group
> + */
> +static int rdt_bit_usage_show(struct kernfs_open_file *of,
> + struct seq_file *seq, void *v)
> +{
> + struct rdt_resource *r = of->kn->parent->priv;
> + u32 sw_shareable, hw_shareable, exclusive;
> + struct rdt_domain *dom;
> + int i, hwb, swb, excl;
> + enum rdtgrp_mode mode;
> + bool sep = false;
> + u32 *ctrl;
> +
> + mutex_lock(&rdtgroup_mutex);
> + hw_shareable = r->cache.shareable_bits;
> + list_for_each_entry(dom, &r->domains, list) {
> + if (sep)
> + seq_puts(seq, ";");
> + ctrl = dom->ctrl_val;
> + sw_shareable = 0;
> + exclusive = 0;
> + seq_printf(seq, "%d=", dom->id);
> + for (i = 0; i < r->num_closid; i++, ctrl++) {
> + if (!closid_allocated(i))
> + continue;
> + mode = rdtgroup_mode_by_closid(i);
> + switch (mode) {
> + case RDT_MODE_SHAREABLE:
> + sw_shareable |= *ctrl;
> + break;
> + case RDT_MODE_EXCLUSIVE:
> + exclusive |= *ctrl;
> + break;
> + case RDT_NUM_MODES:
> + WARN(1,
> + "invalid mode for closid %d\n", i);
> + break;
> + }
> + }
> + for (i = r->cache.cbm_len - 1; i >= 0; i--) {
> + hwb = test_bit(i, (unsigned long *)&hw_shareable);
> + swb = test_bit(i, (unsigned long *)&sw_shareable);
> + excl = test_bit(i, (unsigned long *)&exclusive);
> + if (hwb && swb)
> + seq_puts(seq, "X");
> + else if (hwb && !swb)
> + seq_puts(seq, "H");
> + else if (!hwb && swb)
> + seq_puts(seq, "S");
> + else if (excl)
> + seq_puts(seq, "E");
> + else /* Unused bits remain */
> + seq_puts(seq, "0");
> + }
> + sep = true;
> + }
> + seq_puts(seq, "\n");
> + mutex_unlock(&rdtgroup_mutex);
> + return 0;
> +}


--
~Randy