From: James Morse <james.morse@arm.com>
To: Reinette Chatre <reinette.chatre@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
H Peter Anvin <hpa@zytor.com>, Babu Moger <Babu.Moger@amd.com>,
shameerali.kolothum.thodi@huawei.com,
Jamie Iles <jamie@nuviainc.com>,
D Scott Phillips OS <scott@os.amperecomputing.com>,
lcherian@marvell.com, bobo.shaobowang@huawei.com,
tan.shaopeng@fujitsu.com
Subject: Re: [PATCH v3 15/21] x86/resctrl: Abstract __rmid_read()
Date: Wed, 30 Mar 2022 17:44:29 +0100 [thread overview]
Message-ID: <c2358bf0-1369-f8c3-6b44-e86a44c5016e@arm.com> (raw)
In-Reply-To: <853b9cfd-504d-0dcb-2a2c-8b8df75a9b60@intel.com>
Hi Reinette,
On 16/03/2022 21:52, Reinette Chatre wrote:
> On 2/17/2022 10:21 AM, James Morse wrote:
>> __rmid_read() selects the specified eventid and returns the counter
>> value from the MSR. The error handling is architecture specific, and
>> handled by the callers, rdtgroup_mondata_show() and __mon_event_count().
>>
>> Error handling should be handled by architecture specific code, as
>> a different architecture may have different requirements. MPAM's
>> counters can report that they are 'not ready', requiring a second
>> read after a short delay. This should be hidden from resctrl.
>>
>> Make __rmid_read() the architecture specific function for reading
>> a counter. Rename it resctrl_arch_rmid_read() and move the error
>> handling into it.
>> @@ -180,14 +180,24 @@ static u64 __rmid_read(u32 rmid, enum resctrl_event_id eventid)
>> * are error bits.
>> */
>> wrmsr(MSR_IA32_QM_EVTSEL, eventid, rmid);
>> - rdmsrl(MSR_IA32_QM_CTR, val);
>> + rdmsrl(MSR_IA32_QM_CTR, msr_val);
>>
>> - return val;
>> + if (msr_val & RMID_VAL_ERROR)
>> + return -EIO;
>> + if (msr_val & RMID_VAL_UNAVAIL)
>> + return -EINVAL;
>> +
>> + *val = msr_val;
>> +
>> + return 0;
>> }
>
> From above we see that resctrl_arch_rmid_read() returns an int that could be
> -EIO or -EINVAL ...
>
> ...
>
>> @@ -319,15 +331,15 @@ static u64 __mon_event_count(u32 rmid, struct rmid_read *rr)
>> {
>> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);
>> struct mbm_state *m;
>> - u64 chunks, tval;
>> + u64 chunks, tval = 0;
>>
>> if (rr->first)
>> resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);
>>
>> - tval = __rmid_read(rmid, rr->evtid);
>> - if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
>> - return tval;
>> - }
>> + rr->err = resctrl_arch_rmid_read(rmid, rr->evtid, &tval);
>> + if (rr->err)
>> + return rr->err;
>> +
>
> Setting rr->err, an int, to the return of resctrl_arch_rmid_read() is ok and
> can handle the negative error codes, but returning it here means that
> __mon_event_count()'s return type should be changed,
> it is currently u64.
Good point. Fixed.
>> @@ -419,9 +431,14 @@ void mon_event_count(void *info)
>> }
>> }
>>
>
> Also take care here ... ret_val in mon_event_count() is still u64 while
> __mon_event_count() attempts to return negative errors.
(yup, fixed)
>> - /* Report error if none of rmid_reads are successful */
>> - if (ret_val)
>> - rr->val = ret_val;
>> + /*
>> + * __mon_event_count() calls for newly created monitor groups may
>> + * report -EINVAL/Unavailable if the monitor hasn't seen any traffic.
>> + * If the first call for the control group succeed, discard any error
>> + * set by reads of monitor groups.
>> + */
>
> Additionally, if the first call fails, but a following read of monitor group
> succeeds then the first call's error is discarded.
>
> How about if the last sentence is replaced with:
> "Discard error if any of the monitor event reads succeeded."
Sure,
Thanks,
James
next prev parent reply other threads:[~2022-03-30 16:44 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-17 18:20 [PATCH v3 00/21] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
2022-02-17 18:20 ` [PATCH v3 01/21] x86/resctrl: Kill off alloc_enabled James Morse
2022-03-16 21:48 ` Reinette Chatre
2022-02-17 18:20 ` [PATCH v3 02/21] x86/resctrl: Merge mon_capable and mon_enabled James Morse
2022-02-17 18:20 ` [PATCH v3 03/21] x86/resctrl: Add domain online callback for resctrl work James Morse
2022-02-17 18:20 ` [PATCH v3 04/21] x86/resctrl: Group struct rdt_hw_domain cleanup James Morse
2022-02-17 18:20 ` [PATCH v3 05/21] x86/resctrl: Add domain offline callback for resctrl work James Morse
2022-02-17 18:20 ` [PATCH v3 06/21] x86/resctrl: Remove set_mba_sc()s control array re-initialisation James Morse
2022-02-17 18:20 ` [PATCH v3 07/21] x86/resctrl: Create mba_sc configuration in the rdt_domain James Morse
2022-03-05 0:26 ` Reinette Chatre
2022-03-30 16:43 ` James Morse
2022-03-16 21:50 ` Reinette Chatre
2022-03-30 16:43 ` James Morse
2022-04-01 22:54 ` Reinette Chatre
2022-04-04 16:35 ` James Morse
2022-04-04 20:43 ` Reinette Chatre
2022-02-17 18:20 ` [PATCH v3 08/21] x86/resctrl: Switch over to the resctrl mbps_val list James Morse
2022-02-17 18:20 ` [PATCH v3 09/21] x86/resctrl: Remove architecture copy of mbps_val James Morse
2022-02-17 18:20 ` [PATCH v3 10/21] x86/resctrl: Abstract and use supports_mba_mbps() James Morse
2022-02-17 18:21 ` [PATCH v3 11/21] x86/resctrl: Allow update_mba_bw() to update controls directly James Morse
2022-02-17 18:21 ` [PATCH v3 12/21] x86/resctrl: Calculate bandwidth from the previous __mon_event_count() chunks James Morse
2022-03-05 0:27 ` Reinette Chatre
2022-03-30 16:44 ` James Morse
2022-02-17 18:21 ` [PATCH v3 13/21] x86/recstrl: Add per-rmid arch private storage for overflow and chunks James Morse
2022-03-16 21:50 ` Reinette Chatre
2022-02-17 18:21 ` [PATCH v3 14/21] x86/recstrl: Allow per-rmid arch private storage to be reset James Morse
2022-03-16 21:50 ` Reinette Chatre
2022-02-17 18:21 ` [PATCH v3 15/21] x86/resctrl: Abstract __rmid_read() James Morse
2022-03-16 21:52 ` Reinette Chatre
2022-03-30 16:44 ` James Morse [this message]
2022-02-17 18:21 ` [PATCH v3 16/21] x86/resctrl: Pass the required parameters into resctrl_arch_rmid_read() James Morse
2022-03-23 20:58 ` Rob Herring
2022-03-30 16:45 ` James Morse
2022-02-17 18:21 ` [PATCH v3 17/21] x86/resctrl: Move mbm_overflow_count() " James Morse
2022-02-17 18:21 ` [PATCH v3 18/21] x86/resctrl: Move get_corrected_mbm_count() " James Morse
2022-02-17 18:21 ` [PATCH v3 19/21] x86/resctrl: Rename and change the units of resctrl_cqm_threshold James Morse
2022-03-17 17:00 ` Reinette Chatre
2022-03-30 16:45 ` James Morse
2022-04-01 22:55 ` Reinette Chatre
2022-02-17 18:21 ` [PATCH v3 20/21] x86/resctrl: Add resctrl_rmid_realloc_limit to abstract x86's boot_cpu_data James Morse
2022-02-17 18:21 ` [PATCH v3 21/21] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
2022-03-23 21:17 ` Rob Herring
2022-04-04 16:36 ` James Morse
2022-03-07 12:56 ` [PATCH v3 00/21] " Jamie Iles
2022-04-04 16:36 ` James Morse
2022-03-15 6:41 ` Xin Hao
2022-04-04 16:36 ` James Morse
2022-03-15 8:16 ` tan.shaopeng
2022-04-04 16:35 ` James Morse
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