2023-05-25 18:12:57

by James Morse

Subject: [PATCH v4 03/24] x86/resctrl: Create helper for RMID allocation and mondata dir creation

When monitorrring is support, each monitor and control group is allocated
an RMID. For control groups, rdtgroup_mkdir_ctrl_mon() later goes on to
allocate the CLOSID.

MPAM's equivalent of RMID are not an independent number, so can't be
allocated until the CLOSID is known. An RMID allocation for one CLOSID
may fail, whereas another may succeed depending on how many monitor
groups a control group has.

The RMID allocation needs to move to be after the CLOSID has been
allocated.

To make a subsequent change that does this easier to read, move the RMID
allocation and mondata dir creation to a helper.

Tested-by: Shaopeng Tan <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: James Morse <[email protected]>
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 42 +++++++++++++++++---------
1 file changed, 27 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 023eae69f29e..05774b185eec 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3152,6 +3152,30 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
return ret;
}

+static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
+{
+ int ret;
+
+ if (!rdt_mon_capable)
+ return 0;
+
+ ret = alloc_rmid();
+ if (ret < 0) {
+ rdt_last_cmd_puts("Out of RMIDs\n");
+ return ret;
+ }
+ rdtgrp->mon.rmid = ret;
+
+ ret = mkdir_mondata_all(rdtgrp->kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
+ if (ret) {
+ rdt_last_cmd_puts("kernfs subdir error\n");
+ free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
+ return ret;
+ }
+
+ return 0;
+}
+
static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
const char *name, umode_t mode,
enum rdt_group_type rtype, struct rdtgroup **r)
@@ -3217,20 +3241,10 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
goto out_destroy;
}

- if (rdt_mon_capable) {
- ret = alloc_rmid();
- if (ret < 0) {
- rdt_last_cmd_puts("Out of RMIDs\n");
- goto out_destroy;
- }
- rdtgrp->mon.rmid = ret;
+ ret = mkdir_rdt_prepare_rmid_alloc(rdtgrp);
+ if (ret)
+ goto out_destroy;

- ret = mkdir_mondata_all(kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
- if (ret) {
- rdt_last_cmd_puts("kernfs subdir error\n");
- goto out_idfree;
- }
- }
kernfs_activate(kn);

/*
@@ -3238,8 +3252,6 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
*/
return 0;

-out_idfree:
- free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
out_destroy:
kernfs_put(rdtgrp->kn);
kernfs_remove(rdtgrp->kn);
--
2.39.2

2023-06-15 22:10:51

by Reinette Chatre

Subject: Re: [PATCH v4 03/24] x86/resctrl: Create helper for RMID allocation and mondata dir creation

Hi James,

On 5/25/2023 11:01 AM, James Morse wrote:
> When monitorrring is support, each monitor and control group is allocated

"When monitorrring is support" -> "When monitoring is supported"?

> an RMID. For control groups, rdtgroup_mkdir_ctrl_mon() later goes on to
> allocate the CLOSID.
>
> MPAM's equivalent of RMID are not an independent number, so can't be
> allocated until the CLOSID is known. An RMID allocation for one CLOSID
> may fail, whereas another may succeed depending on how many monitor
> groups a control group has.
>
> The RMID allocation needs to move to be after the CLOSID has been
> allocated.
>
> To make a subsequent change that does this easier to read, move the RMID
> allocation and mondata dir creation to a helper.

(nitpick) Could you please swap the two parts of the sentence to make the
changelog easier to parse? "Move the RMID allocation and mondata dir
creation to a helper to make the subsequent change that does this
easier to read."

>
> Tested-by: Shaopeng Tan <[email protected]>
> Reviewed-by: Ilpo Järvinen <[email protected]>
> Signed-off-by: James Morse <[email protected]>

Reinette