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SubjectRe: [PATCH 2/2] x86/resctrl: Initialize new resource group with default MBA values
On Wed, Apr 10, 2019 at 03:55:28AM +0800, Xiaochen Shen wrote:
> Currently when a new resource group is created, the allocation values
> of MBA resource are not initialized and remain meaningless data.
>
> For example:
> mkdir /sys/fs/resctrl/p1
> cat /sys/fs/resctrl/p1/schemata
> MB:0=100;1=100
>
> echo "MB:0=10;1=20" > /sys/fs/resctrl/p1/schemata
> cat /sys/fs/resctrl/p1/schemata
> MB:0= 10;1= 20
>
> rmdir /sys/fs/resctrl/p1
> mkdir /sys/fs/resctrl/p2
> cat /sys/fs/resctrl/p2/schemata
> MB:0= 10;1= 20
>
> When the new group is created, it is reasonable to initialize MBA
> resource with default values.
>
> Initialize MBA resource and cache resources in separate functions.

Please format your commit message by indenting the examples:

x86/resctrl: Initialize a new resource group with default MBA values

Currently, when a new resource group is created, the allocation values
of the MBA resource are not initialized and remain meaningless data.

For example:

mkdir /sys/fs/resctrl/p1
cat /sys/fs/resctrl/p1/schemata
MB:0=100;1=100

echo "MB:0=10;1=20" > /sys/fs/resctrl/p1/schemata
cat /sys/fs/resctrl/p1/schemata
MB:0= 10;1= 20

rmdir /sys/fs/resctrl/p1
mkdir /sys/fs/resctrl/p2
cat /sys/fs/resctrl/p2/schemata
MB:0= 10;1= 20

Therefore, when the new group is created, it is reasonable to initialize
MBA resource with default values.

Initialize the MBA resource and cache resources in separate functions."

Thx.

>
> Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
> Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
> ---
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 4 +-
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 139 ++++++++++++++++--------------
> 2 files changed, 75 insertions(+), 68 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 2dbd990..576bb6a 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -342,10 +342,10 @@ int update_domains(struct rdt_resource *r, int closid)
> if (cpumask_empty(cpu_mask) || mba_sc)
> goto done;
> cpu = get_cpu();
> - /* Update CBM on this cpu if it's in cpu_mask. */
> + /* Update resource control msr on this cpu if it's in cpu_mask. */

s/cpu/CPU/g

> if (cpumask_test_cpu(cpu, cpu_mask))
> rdt_ctrl_update(&msr_param);
> - /* Update CBM on other cpus. */
> + /* Update resource control msr on other cpus. */

Ditto.

> smp_call_function_many(cpu_mask, rdt_ctrl_update, &msr_param, 1);
> put_cpu();
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 08e0333..9f12a02 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2516,8 +2516,8 @@ static void cbm_ensure_valid(u32 *_val, struct rdt_resource *r)
> bitmap_clear(val, zero_bit, cbm_len - zero_bit);
> }
>
> -/**
> - * rdtgroup_init_alloc - Initialize the new RDT group's allocations
> +/*
> + * Initialize cache resources with default values.
> *
> * A new RDT group is being created on an allocation capable (CAT)
> * supporting system. Set this group up to start off with all usable
> @@ -2526,85 +2526,92 @@ static void cbm_ensure_valid(u32 *_val, struct rdt_resource *r)
> * All-zero CBM is invalid. If there are no more shareable bits available
> * on any domain then the entire allocation will fail.
> */
> -static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
> +static int rdtgroup_init_cat(struct rdt_resource *r, u32 closid)
> {
> struct rdt_resource *r_cdp = NULL;
> struct rdt_domain *d_cdp = NULL;
> u32 used_b = 0, unused_b = 0;
> - u32 closid = rdtgrp->closid;
> - struct rdt_resource *r;
> unsigned long tmp_cbm;
> enum rdtgrp_mode mode;
> struct rdt_domain *d;
> u32 peer_ctl, *ctrl;
> - int i, ret;
> + int i;
>
> - for_each_alloc_enabled_rdt_resource(r) {
> + list_for_each_entry(d, &r->domains, list) {
> + rdt_cdp_peer_get(r, d, &r_cdp, &d_cdp);
> + d->have_new_ctrl = false;
> + d->new_ctrl = r->cache.shareable_bits;
> + used_b = r->cache.shareable_bits;
> + ctrl = d->ctrl_val;
> + for (i = 0; i < closids_supported(); i++, ctrl++) {
> + if (closid_allocated(i) && i != closid) {
> + mode = rdtgroup_mode_by_closid(i);
> + if (mode == RDT_MODE_PSEUDO_LOCKSETUP)
> + break;
> + /*
> + * If CDP is active include peer
> + * domain's usage to ensure there
> + * is no overlap with an exclusive
> + * group.
> + */
> + if (d_cdp)
> + peer_ctl = d_cdp->ctrl_val[i];
> + else
> + peer_ctl = 0;
> + used_b |= *ctrl | peer_ctl;
> + if (mode == RDT_MODE_SHAREABLE)
> + d->new_ctrl |= *ctrl | peer_ctl;
> + }
> + }
> + if (d->plr && d->plr->cbm > 0)
> + used_b |= d->plr->cbm;
> + unused_b = used_b ^ (BIT_MASK(r->cache.cbm_len) - 1);
> + unused_b &= BIT_MASK(r->cache.cbm_len) - 1;
> + d->new_ctrl |= unused_b;
> + cbm_ensure_valid(&d->new_ctrl, r);
> /*
> - * Only initialize default allocations for CBM cache
> - * resources
> + * Assign the u32 CBM to an unsigned long to ensure
> + * that bitmap_weight() does not access out-of-bound
> + * memory.
> */

So all this code working on a rdt_domain *d pointer could be carved out
into a separate function called something like:

__init_one_rdt_domain(d, ...)

and this will make the code more readable and save us at least 2
indentation levels.

Please do that in a preparatory patch.

> - if (r->rid == RDT_RESOURCE_MBA)
> - continue;

Then, after having done that, it would be very obvious when you do this
above because you won't be calling that __init_one_rdt_domain() function
for an MBA anyway.

Thx.

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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