linux-kernel - Re: [PATCH v8 10/13] x86/resctrl: Add sysfs interface to write mbm_total_bytes

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Date:   Mon, 7 Nov 2022 13:00:11 -0600
From:   "Moger, Babu" <babu.moger@....com>
To:     Peter Newman <peternewman@...gle.com>
Cc:     akpm@...ux-foundation.org, bagasdotme@...il.com, bp@...en8.de,
        chang.seok.bae@...el.com, corbet@....net,
        damien.lemoal@...nsource.wdc.com, daniel.sneddon@...ux.intel.com,
        dave.hansen@...ux.intel.com, eranian@...gle.com,
        fenghua.yu@...el.com, hpa@...or.com, james.morse@....com,
        jmattson@...gle.com, jpoimboe@...nel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, paulmck@...nel.org,
        pawan.kumar.gupta@...ux.intel.com, pbonzini@...hat.com,
        peterz@...radead.org, quic_neeraju@...cinc.com,
        rdunlap@...radead.org, reinette.chatre@...el.com,
        sandipan.das@....com, songmuchun@...edance.com, tglx@...utronix.de,
        tony.luck@...el.com, x86@...nel.org
Subject: Re: [PATCH v8 10/13] x86/resctrl: Add sysfs interface to write
 mbm_total_bytes_config


On 11/7/22 04:21, Peter Newman wrote:
> Hi Babu,
>
> On Fri, Nov 04, 2022 at 03:01:09PM -0500, Babu Moger wrote:
>> +	/*
>> +	 * When an Event Configuration is changed, the bandwidth counters
>> +	 * for all RMIDs and Events will be cleared by the hardware. The
>> +	 * hardware also sets MSR_IA32_QM_CTR.Unavailable (bit 62) for
>> +	 * every RMID on the next read to any event for every RMID.
>> +	 * Subsequent reads will have MSR_IA32_QM_CTR.Unavailable (bit 62)
>> +	 * cleared while it is tracked by the hardware. Clear the
>> +	 * mbm_local and mbm_total counts for all the RMIDs.
>> +	 */
>> +	memset(d->mbm_local, 0, sizeof(struct mbm_state) * r->num_rmid);
>> +	memset(d->mbm_total, 0, sizeof(struct mbm_state) * r->num_rmid);
> Looking around, I can't find a reader for mbm_total anymore. It looks
> like the last place it was used went away in James's recent change:
>
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fall%2F20220902154829.30399-19-james.morse%40arm.com&amp;data=05%7C01%7Cbabu.moger%40amd.com%7C84a9d0f934894a3031a608dac0a9db33%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638034133003350939%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=i3isjCzxnBp4b2VblC7ZpH3hShUEe7unKiKfngG1kzE%3D&amp;reserved=0
>
> Are we supposed to be clearing arch_mbm_total now?
>
Patch got garbled in previous response.

Here is it now.

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 6b222f8e58ae..28d9d99a639e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1517,7 +1517,7 @@ static int mbm_config_write(struct rdt_resource *r,
struct rdt_domain *d,
                            u32 evtid, u32 val)
 {
        struct mon_config_info mon_info = {0};
-       int ret = 0;
+       int ret = 0, i;
 
        rdt_last_cmd_clear();
 
@@ -1557,8 +1557,10 @@ static int mbm_config_write(struct rdt_resource *r,
struct rdt_domain *d,
         * cleared while it is tracked by the hardware. Clear the
         * mbm_local and mbm_total counts for all the RMIDs.
         */
-       memset(d->mbm_local, 0, sizeof(struct mbm_state) * r->num_rmid);
-       memset(d->mbm_total, 0, sizeof(struct mbm_state) * r->num_rmid);
+       for (i = 0; i < r->num_rmid; i++) {
+               resctrl_arch_reset_rmid(r, d, i, QOS_L3_MBM_TOTAL_EVENT_ID);
+               resctrl_arch_reset_rmid(r, d, i, QOS_L3_MBM_LOCAL_EVENT_ID);
+       }
 
 write_exit:
        return ret;

Tthanks

Babu