__mon_event_count() does the per-RMID, per-domain work for
user-initiated event count reads and the initialization of new monitor
groups.
In the initialization case, after resctrl_arch_reset_rmid() calls
__rmid_read() to record an initial count for a new monitor group, it
immediately calls resctrl_arch_rmid_read(). This re-read of the hardware
counter is unnecessary.
Following return from resctrl_arch_reset_rmid(), just clear the
mbm_state and return.
Also, move the mbm_state lookup into the rr->first case, as it's not
needed for regular event count reads: the QOS_L3_OCCUP_EVENT_ID case was
redundant with the accumulating logic at the end of the function.
Signed-off-by: Peter Newman <[email protected]>
---
arch/x86/kernel/cpu/resctrl/monitor.c | 43 ++++++++++++---------------
1 file changed, 19 insertions(+), 24 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 77538abeb72a..e708df478077 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -366,41 +366,36 @@ void free_rmid(u32 rmid)
list_add_tail(&entry->list, &rmid_free_lru);
}
+static struct mbm_state *get_mbm_state(struct rdt_domain *d, u32 rmid,
+ enum resctrl_event_id evtid)
+{
+ switch (evtid) {
+ case QOS_L3_MBM_TOTAL_EVENT_ID:
+ return &d->mbm_total[rmid];
+ case QOS_L3_MBM_LOCAL_EVENT_ID:
+ return &d->mbm_local[rmid];
+ default:
+ return NULL;
+ }
+}
+
static int __mon_event_count(u32 rmid, struct rmid_read *rr)
{
struct mbm_state *m;
u64 tval = 0;
- if (rr->first)
+ if (rr->first) {
resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);
+ m = get_mbm_state(rr->d, rmid, rr->evtid);
+ if (m)
+ memset(m, 0, sizeof(struct mbm_state));
+ return 0;
+ }
rr->err = resctrl_arch_rmid_read(rr->r, rr->d, rmid, rr->evtid, &tval);
if (rr->err)
return rr->err;
- switch (rr->evtid) {
- case QOS_L3_OCCUP_EVENT_ID:
- rr->val += tval;
- return 0;
- case QOS_L3_MBM_TOTAL_EVENT_ID:
- m = &rr->d->mbm_total[rmid];
- break;
- case QOS_L3_MBM_LOCAL_EVENT_ID:
- m = &rr->d->mbm_local[rmid];
- break;
- default:
- /*
- * Code would never reach here because an invalid
- * event id would fail in resctrl_arch_rmid_read().
- */
- return -EINVAL;
- }
-
- if (rr->first) {
- memset(m, 0, sizeof(struct mbm_state));
- return 0;
- }
-
rr->val += tval;
return 0;
--
2.39.0.rc1.256.g54fd8350bd-goog
Hi Peter,
On 12/14/2022 8:08 AM, Peter Newman wrote:
> __mon_event_count() does the per-RMID, per-domain work for
> user-initiated event count reads and the initialization of new monitor
> groups.
>
> In the initialization case, after resctrl_arch_reset_rmid() calls
> __rmid_read() to record an initial count for a new monitor group, it
> immediately calls resctrl_arch_rmid_read(). This re-read of the hardware
> counter is unnecessary.
"... and the following computations are ignored by the caller during
initialization."
>
> Following return from resctrl_arch_reset_rmid(), just clear the
> mbm_state and return.
>
> Also, move the mbm_state lookup into the rr->first case, as it's not
> needed for regular event count reads: the QOS_L3_OCCUP_EVENT_ID case was
> redundant with the accumulating logic at the end of the function.
Starting the above with "Also" creates impression that two logical
changes are merged into a single patch. Since this is not the case you
can avoid the impression with something like:
Following return from resctrl_arch_reset_rmid(), just clear the
mbm_state and return. This involves moving the mbm_state lookup into
the rr->first case, as it's not needed for regular event count reads:
the QOS_L3_OCCUP_EVENT_ID case was redundant with the accumulating logic
at the end of the function.
>
> Signed-off-by: Peter Newman <[email protected]>
> ---
> arch/x86/kernel/cpu/resctrl/monitor.c | 43 ++++++++++++---------------
> 1 file changed, 19 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 77538abeb72a..e708df478077 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -366,41 +366,36 @@ void free_rmid(u32 rmid)
> list_add_tail(&entry->list, &rmid_free_lru);
> }
>
> +static struct mbm_state *get_mbm_state(struct rdt_domain *d, u32 rmid,
> + enum resctrl_event_id evtid)
> +{
> + switch (evtid) {
> + case QOS_L3_MBM_TOTAL_EVENT_ID:
> + return &d->mbm_total[rmid];
> + case QOS_L3_MBM_LOCAL_EVENT_ID:
> + return &d->mbm_local[rmid];
> + default:
> + return NULL;
> + }
> +}
> +
> static int __mon_event_count(u32 rmid, struct rmid_read *rr)
> {
> struct mbm_state *m;
> u64 tval = 0;
>
> - if (rr->first)
> + if (rr->first) {
> resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);
> + m = get_mbm_state(rr->d, rmid, rr->evtid);
> + if (m)
> + memset(m, 0, sizeof(struct mbm_state));
> + return 0;
> + }
>
> rr->err = resctrl_arch_rmid_read(rr->r, rr->d, rmid, rr->evtid, &tval);
> if (rr->err)
> return rr->err;
>
> - switch (rr->evtid) {
> - case QOS_L3_OCCUP_EVENT_ID:
> - rr->val += tval;
> - return 0;
> - case QOS_L3_MBM_TOTAL_EVENT_ID:
> - m = &rr->d->mbm_total[rmid];
> - break;
> - case QOS_L3_MBM_LOCAL_EVENT_ID:
> - m = &rr->d->mbm_local[rmid];
> - break;
> - default:
> - /*
> - * Code would never reach here because an invalid
> - * event id would fail in resctrl_arch_rmid_read().
> - */
> - return -EINVAL;
> - }
> -
> - if (rr->first) {
> - memset(m, 0, sizeof(struct mbm_state));
> - return 0;
> - }
> -
> rr->val += tval;
>
> return 0;
Thank you very much.
Reviewed-by: Reinette Chatre <[email protected]>
Reinette