Date:   Wed, 12 Jan 2022 01:05:51 -0700
From:   Yu Zhao <yuzhao@google.com>
To:     "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andi Kleen <ak@linux.intel.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Hillf Danton <hdanton@sina.com>, Jens Axboe <axboe@kernel.dk>,
        Jesse Barnes <jsbarnes@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Matthew Wilcox <willy@infradead.org>,
        Mel Gorman <mgorman@suse.de>,
        Michael Larabel <Michael@michaellarabel.com>,
        Michal Hocko <mhocko@kernel.org>,
        Rik van Riel <riel@surriel.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Will Deacon <will@kernel.org>,
        Ying Huang <ying.huang@intel.com>,
        linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        page-reclaim@google.com, x86@kernel.org,
        Konstantin Kharlamov <Hi-Angel@yandex.ru>
Subject: Re: [PATCH v6 7/9] mm: multigenerational lru: eviction
Message-ID: <Yd6L349/aJd8hbYn@google.com>
References: <20220104202227.2903605-1-yuzhao@google.com>
 <20220104202227.2903605-8-yuzhao@google.com>
 <87czkyzhfe.fsf@linux.ibm.com>
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On Tue, Jan 11, 2022 at 04:07:57PM +0530, Aneesh Kumar K.V wrote:
> ...
> 
>  +static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness,
> > +			  int *type_scanned, struct list_head *list)
> > +{
> > +	int i;
> > +	int type;
> > +	int scanned;
> > +	int tier = -1;
> > +	DEFINE_MIN_SEQ(lruvec);
> > +
> > +	VM_BUG_ON(!seq_is_valid(lruvec));
> > +
> > +	/*
> > +	 * Try to make the obvious choice first. When anon and file are both
> > +	 * available from the same generation, interpret swappiness 1 as file
> > +	 * first and 200 as anon first.
> > +	 */
> > +	if (!swappiness)
> > +		type = 1;
> > +	else if (min_seq[0] < min_seq[1])
> > +		type = 0;
> > +	else if (swappiness == 1)
> > +		type = 1;
> > +	else if (swappiness == 200)
> > +		type = 0;
> > +	else
> > +		type = get_type_to_scan(lruvec, swappiness, &tier);
> > +
> 
> Wondering wether it will make it simpler to use
> #define ANON 0
> #define FILE 1
> 
> and then
> 	else if (min_seq[ANON] < min_seq[FILE])
> 		type = ANON;
> 
> The usage of 0/1 across code do confuse

I agree, and I plan to do this later because the existing code uses
this convention and needs renaming too.