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Date:   Fri, 28 Jul 2023 17:35:20 +0100
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From:   James Morse <james.morse@arm.com>
Subject: Re: [PATCH v4 08/24] x86/resctrl: Allocate the cleanest CLOSID by
 searching closid_num_dirty_rmid
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,
        D Scott Phillips OS <scott@os.amperecomputing.com>,
        carl@os.amperecomputing.com, lcherian@marvell.com,
        bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com,
        xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com,
        Jamie Iles <quic_jiles@quicinc.com>,
        Xin Hao <xhao@linux.alibaba.com>, peternewman@google.com,
        dfustini@baylibre.com
References: <20230525180209.19497-1-james.morse@arm.com>
 <20230525180209.19497-9-james.morse@arm.com>
 <348034b1-7bca-a8cf-b5bc-36c656de0bd3@intel.com>
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Hi Reinette,

On 6/15/23 23:09, Reinette Chatre wrote:
> On 5/25/2023 11:01 AM, James Morse wrote:
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index 1e7fa40ee471..128d4c7206e4 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -379,6 +379,51 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 closid)
>>   	return ERR_PTR(-ENOSPC);
>>   }
>>   
>> +/**
>> + * resctrl_find_cleanest_closid() - Find a CLOSID where all the associated
>> + *                                  RMID are clean, or the CLOSID that has
>> + *                                  the most clean RMID.
>> + *
>> + * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocated CLOSID
>> + * may not be able to allocate clean RMID. To avoid this the allocator will
>> + * choose the CLOSID with the most clean RMID.
>> + *
>> + * When the CLOSID and RMID are independent numbers, the first free CLOSID will
>> + * be returned.
>> + *
>> + * Call when CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is defined. If not, call
>> + * resctrl_closid_alloc_first_free() instead.
> 
> I was not able to find where resctrl_closid_alloc_first_free() is introduced.

Oops, this was the name for the other half of closid_alloc() back when I thought it was more
readable to give it a name. The version posted leaves it alone to reduce the churn. I'll drop this paragraph.


Thanks,

James