linux-kernel - Re: [PATCH v4 06/24] x86/resctrl: Track the number of dirty RMID a CLOSID has

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Message-ID: <8cee8203-1bce-3e71-d8df-2a3fcde43967@arm.com>
Date:   Fri, 28 Jul 2023 17:35:33 +0100
From:   James Morse <james.morse@....com>
To:     Reinette Chatre <reinette.chatre@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Babu Moger <Babu.Moger@....com>,
        shameerali.kolothum.thodi@...wei.com,
        D Scott Phillips OS <scott@...amperecomputing.com>,
        carl@...amperecomputing.com, lcherian@...vell.com,
        bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
        xingxin.hx@...nanolis.org, baolin.wang@...ux.alibaba.com,
        Jamie Iles <quic_jiles@...cinc.com>,
        Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
        dfustini@...libre.com
Subject: Re: [PATCH v4 06/24] x86/resctrl: Track the number of dirty RMID a
 CLOSID has

Hi Reinette,

On 6/15/23 23:08, Reinette Chatre wrote:
> On 5/25/2023 11:01 AM, James Morse wrote:
>> @@ -420,6 +438,9 @@ static void add_rmid_to_limbo(struct rmid_entry *entry)
>>   		rmid_limbo_count++;
>>   	else
>>   		list_add_tail(&entry->list, &rmid_free_lru);
>> +
>> +	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID))
>> +		closid_num_dirty_rmid[entry->closid]++;
   
> Wouldn't this always increment the counter, whether the entry is
> dirty or not? (Although ... the later change where entries are
> always dirty may make this correct ... although I would still
> expect the if statement that precedes it to change).

True, I was expecting add_rmid_to_limbo() to always transiently add CLOSID to limbo,
hence this is unconditional, but you're right its optional - and this could cause everything
to pile up in the list when the limbo handler isn't running.
I'll add a check on entry->busy, and move this into the above if case.


Thanks,

James