From: James Morse <james.morse@arm.com>
To: Rob Herring <robh@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Fenghua Yu <fenghua.yu@intel.com>,
Reinette Chatre <reinette.chatre@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 21/21] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes
Date: Mon, 4 Apr 2022 17:36:02 +0100 [thread overview]
Message-ID: <30d85009-f4be-25b1-7eb8-eea4b3058e27@arm.com> (raw)
In-Reply-To: <YjuOWpqLfiP4u2AT@robh.at.kernel.org>
Hi Rob,
On 3/23/22 21:17, Rob Herring wrote:
> On Thu, Feb 17, 2022 at 06:21:10PM +0000, James Morse wrote:
>> resctrl_arch_rmid_read() returns a value in chunks, as read from the
>> hardware. This needs scaling to bytes by mon_scale, as provided by
>> the architecture code.
>>
>> Now that resctrl_arch_rmid_read() performs the overflow and corrections
>> itself, it may as well return a value in bytes directly. This allows
>> the accesses to the architecture specific 'hw' structure to be removed.
>>
>> Move the mon_scale conversion into resctrl_arch_rmid_read().
>> mbm_bw_count() is updated to calculate bandwidth from bytes.
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index 3a6555f49720..437e7db77f93 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -211,10 +211,11 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,
>> if (am) {
>> am->chunks += mbm_overflow_count(am->prev_msr, msr_val,
>> hw_res->mbm_width);
>> - *val = get_corrected_mbm_count(rmid, am->chunks);
>> + chunks = get_corrected_mbm_count(rmid, am->chunks);
>> + *val = chunks * hw_res->mon_scale;
>
> This can be moved out of the if/else if you make the following change:
>
>> am->prev_msr = msr_val;
>> } else {
>> - *val = msr_val;
>> + *val = msr_val * hw_res->mon_scale;
>
> chunks = msr_val;
>
>> }
Sure, I guess it makes sense to only set *val in one place.
>>
>> return 0;
>> @@ -400,15 +397,14 @@ static u64 __mon_event_count(u32 rmid, struct rmid_read *rr)
>> */
>> static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
>> {
>> - struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);
>> struct mbm_state *m = &rr->d->mbm_local[rmid];
>> - u64 cur_bw, chunks, cur_chunks;
>> + u64 cur_bw, bytes, cur_bytes;
>>
>> - cur_chunks = rr->val;
>> - chunks = cur_chunks - m->prev_bw_chunks;
>> - m->prev_bw_chunks = cur_chunks;
>> + cur_bytes = rr->val;
>> + bytes = cur_bytes - m->prev_bw_bytes;
>> + m->prev_bw_bytes = cur_bytes;
>>
>> - cur_bw = (chunks * hw_res->mon_scale) >> 20;
>> + cur_bw = bytes >> 20;
>
> 'bytes / SZ_1M' would be more readable and any decent compiler should
> optimize a power of 2 divide. But maybe that's a separate change as
> there are other cases of bytes to MB.
I agree its more readable. As I've touched this one, I'll change it.
Thanks,
James
next prev parent reply other threads:[~2022-04-04 21:23 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
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 [this message]
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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