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Date: Thu, 20 Jun 2024 09:46:04 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
fenghua.yu@...el.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com
Cc: x86@...nel.org, hpa@...or.com, paulmck@...nel.org, rdunlap@...radead.org,
tj@...nel.org, peterz@...radead.org, yanjiewtw@...il.com,
kim.phillips@....com, lukas.bulwahn@...il.com, seanjc@...gle.com,
jmattson@...gle.com, leitao@...ian.org, jpoimboe@...nel.org,
rick.p.edgecombe@...el.com, kirill.shutemov@...ux.intel.com,
jithu.joseph@...el.com, kai.huang@...el.com, kan.liang@...ux.intel.com,
daniel.sneddon@...ux.intel.com, pbonzini@...hat.com, sandipan.das@....com,
ilpo.jarvinen@...ux.intel.com, peternewman@...gle.com,
maciej.wieczor-retman@...el.com, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, eranian@...gle.com, james.morse@....com
Subject: Re: [PATCH v4 16/19] x86/resctrl: Enable ABMC by default on resctrl
mount
Hi Reinette,
On 6/13/24 20:50, Reinette Chatre wrote:
> Hi Babu,
>
> On 5/24/24 5:23 AM, Babu Moger wrote:
>> Enable ABMC by default when feature is supported.
>
> Why enable/disable it on every mount/unmount cycle though? Why not just
> enable it at the beginning and only change if requested by user?
I think we can do that. This needs to be done at __init
rdt_get_mon_l3_config(). Will let you if i see any issues with that.
>
>>
>> Counters are assigned automatically on group creation. If the counters
>> are exhausted, report the warnings and continue. It is not required to
>> fail group creation for assignment failures. Users will have the option
>> to modify the assignments.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v4: Few name changes based on the upstream discussion.
>> Commit message update.
>>
>> v3: This is a new patch. Patch addresses the upstream comment to enable
>> ABMC feature by default if the feature is available.
>> ---
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 69 ++++++++++++++++++++++++++
>> 1 file changed, 69 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 5ea1e58c7201..f452b6d9bb99 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -2756,6 +2756,7 @@ static void rdt_disable_ctx(void)
>> {
>> resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
>> resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
>> + resctrl_abmc_disable(RDT_RESOURCE_L3);
>> set_mba_sc(false);
>> resctrl_debug = false;
>> @@ -2786,6 +2787,8 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
>> if (ctx->enable_debug)
>> resctrl_debug = true;
>> + resctrl_abmc_enable(RDT_RESOURCE_L3);
>> +
>> return 0;
>> out_cdpl3:
>> @@ -2882,6 +2885,41 @@ static void schemata_list_destroy(void)
>> }
>> }
>> +static int resctrl_assign_events(struct rdtgroup *rdtgrp)
>> +{
>> + struct rdt_resource *r =
>> &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
>> + struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
>> + int ret = 0;
>> +
>> + if (!hw_res->abmc_enabled)
>> + return 0;
>
> resctrl fs should not be peeking in arch structure
Sure.
>
>> +
>> + if (is_mbm_total_enabled())
>> + ret = resctrl_grp_assign(rdtgrp, QOS_L3_MBM_TOTAL_EVENT_ID);
>> +
>> + if (!ret && is_mbm_local_enabled())
>> + ret = resctrl_grp_assign(rdtgrp, QOS_L3_MBM_LOCAL_EVENT_ID);
>> +
>
> This function needs a comment about why it is ok to return with error and
> partial changes.
Sure.
>
>> + return ret;
>> +}
>> +
>> +static int resctrl_unassign_events(struct rdtgroup *rdtgrp)
>> +{
>> + struct rdt_resource *r =
>> &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
>> + struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
>> + int ret = 0;
>> +
>> + if (!hw_res->abmc_enabled)
>> + return 0;
>> +
>> + if (is_mbm_total_enabled())
>> + ret = resctrl_grp_unassign(rdtgrp, QOS_L3_MBM_TOTAL_EVENT_ID);
>> +
>> + if (!ret && is_mbm_local_enabled())
>> + ret = resctrl_grp_unassign(rdtgrp, QOS_L3_MBM_LOCAL_EVENT_ID);
>> + return ret;
>> +}
>> +
>> static int rdt_get_tree(struct fs_context *fc)
>> {
>> struct rdt_fs_context *ctx = rdt_fc2context(fc);
>> @@ -2941,6 +2979,14 @@ static int rdt_get_tree(struct fs_context *fc)
>> if (ret < 0)
>> goto out_mongrp;
>> rdtgroup_default.mon.mon_data_kn = kn_mondata;
>> +
>> + /*
>> + * Assign the monitor counters if it is available. If it fails,
>> + * report the warnings and continue. It is not nessaccery to
>> + * fail here.
>> + */
>
> nessaccery -> necessary
Sure.
>
> Please elaborate why it is not necessary to fail.
Sure.
>
>
>> + if (resctrl_assign_events(&rdtgroup_default) < 0)
>> + rdt_last_cmd_puts("Monitor assignment failed\n");
>
> How will user know that there is a warning? This does not return an error
> so nothing will prompt user to check the status file. Perhaps add a comment
> in the docs to help users at least know that this exists. Another helpful
Sure. Will add text about this in the documentation.
> thing will be to have the counter return "Unassigned" if it has not been
> assigned
> since users familiar with old interface may see "Unavailable" without
> knowing that user action is required to get a working event.
Not so sure about interpreting hardware reported error.
>
>> }
>> ret = rdt_pseudo_lock_init();
>> @@ -3214,6 +3260,8 @@ static void rdt_kill_sb(struct super_block *sb)
>> cpus_read_lock();
>> mutex_lock(&rdtgroup_mutex);
>> + resctrl_unassign_events(&rdtgroup_default);
>> +
>> rdt_disable_ctx();
>> /*Put everything back to default values. */
>> @@ -3752,6 +3800,14 @@ static int rdtgroup_mkdir_mon(struct kernfs_node
>> *parent_kn,
>> goto out_unlock;
>> }
>> + /*
>> + * Assign the monitor counters if it is available. If it fails,
>> + * report the warnings and continue. It is not nessaccery to
>> + * fail here.
>> + */
>
> Fix copy&paste here and below.
Sure.
>
>> + if (resctrl_assign_events(rdtgrp) < 0)
>> + rdt_last_cmd_puts("Monitor assignment failed\n");
>> +
>> kernfs_activate(rdtgrp->kn);
>> /*
>> @@ -3796,6 +3852,14 @@ static int rdtgroup_mkdir_ctrl_mon(struct
>> kernfs_node *parent_kn,
>> if (ret)
>> goto out_closid_free;
>> + /*
>> + * Assign the monitor counters if it is available. If it fails,
>> + * report the warnings and continue. It is not nessaccery to
>> + * fail here.
>> + */
>> + if (resctrl_assign_events(rdtgrp) < 0)
>> + rdt_last_cmd_puts("Monitor assignment failed\n");
>> +
>> kernfs_activate(rdtgrp->kn);
>> ret = rdtgroup_init_alloc(rdtgrp);
>> @@ -3891,6 +3955,9 @@ static int rdtgroup_rmdir_mon(struct rdtgroup
>> *rdtgrp, cpumask_var_t tmpmask)
>> update_closid_rmid(tmpmask, NULL);
>> rdtgrp->flags = RDT_DELETED;
>> +
>> + resctrl_unassign_events(rdtgrp);
>> +
>> free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
>> /*
>> @@ -3937,6 +4004,8 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup
>> *rdtgrp, cpumask_var_t tmpmask)
>> cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
>> update_closid_rmid(tmpmask, NULL);
>> + resctrl_unassign_events(rdtgrp);
>> +
>> free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
>> closid_free(rdtgrp->closid);
>>
>
> Reinette
>
--
Thanks
Babu Moger
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