Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.32 as permitted sender) client-ip=23.128.96.32;
Message-ID: <d0079d15-9950-5c74-75e9-aed848b48ea4@arm.com>
Date:   Wed, 13 Dec 2023 18:04:09 +0000
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101
 Thunderbird/102.13.0
Subject: Re: [PATCH v7 05/24] x86/resctrl: Track the closid with the rmid
Content-Language: en-GB
To:     babu.moger@amd.com, x86@kernel.org, linux-kernel@vger.kernel.org
Cc:     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>,
        shameerali.kolothum.thodi@huawei.com,
        D Scott Phillips OS <scott@os.amperecomputing.com>,
        carl@os.amperecomputing.com, lcherian@marvell.com,
        bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com,
        baolin.wang@linux.alibaba.com, Jamie Iles <quic_jiles@quicinc.com>,
        Xin Hao <xhao@linux.alibaba.com>, peternewman@google.com,
        dfustini@baylibre.com, amitsinght@marvell.com
References: <20231025180345.28061-1-james.morse@arm.com>
 <20231025180345.28061-6-james.morse@arm.com>
 <77d92d3e-7259-418f-8b3a-e245dbc3d259@amd.com>
From:   James Morse <james.morse@arm.com>
In-Reply-To: <77d92d3e-7259-418f-8b3a-e245dbc3d259@amd.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Babu,

On 09/11/2023 20:31, Moger, Babu wrote:
> On 10/25/23 13:03, James Morse wrote:
>> x86's RMID are independent of the CLOSID. An RMID can be allocated,
>> used and freed without considering the CLOSID.
>>
>> MPAM's equivalent feature is PMG, which is not an independent number,
>> it extends the CLOSID/PARTID space. For MPAM, only PMG-bits worth of
>> 'RMID' can be allocated for a single CLOSID.
>> i.e. if there is 1 bit of PMG space, then each CLOSID can have two
>> monitor groups.
>>
>> To allow resctrl to disambiguate RMID values for different CLOSID,
>> everything in resctrl that keeps an RMID value needs to know the CLOSID
>> too. This will always be ignored on x86.

>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index 5d9864919f1c..2a0233cd0bc9 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -285,9 +300,9 @@ void __check_limbo(struct rdt_domain *d, bool force_free)
>>  		if (nrmid >= r->num_rmid)
>>  			break;
>>  
>> -		entry = __rmid_entry(nrmid);
>> +		entry = __rmid_entry(X86_RESCTRL_EMPTY_CLOSID, nrmid);// temporary
> 
> What is temporary means here? Can you please elaborate(or remove)?

It means this line gets removed in a subsequent patch - don't spend too long rationalising
the values used. This one gets removed in the next patch as __check_limbo() is changed to
operate by index instead.


Thanks,

James