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Message-ID: <3c3a4dce-980d-0405-d269-1da9e62b1344@linux.intel.com>
Date: Fri, 13 Jul 2018 03:48:28 -0700
From: Dave Hansen <dave.hansen@...ux.intel.com>
To: "Huang, Ying" <ying.huang@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Michal Hocko <mhocko@...e.com>,
Johannes Weiner <hannes@...xchg.org>,
Shaohua Li <shli@...nel.org>, Hugh Dickins <hughd@...gle.com>,
Minchan Kim <minchan@...nel.org>,
Rik van Riel <riel@...hat.com>,
Daniel Jordan <daniel.m.jordan@...cle.com>,
Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH 1/6] swap: Add comments to lock_cluster_or_swap_info()
> +/*
> + * At most times, fine grained cluster lock is sufficient to protect
Can we call out those times, please?
> + * the operations on sis->swap_map.
Please be careful with the naming. You can call it 'si' because that's
what the function argument is named. Or, swap_info_struct because
that's the struct name. Calling it 'sis' is a bit sloppy, no?
> No need to acquire gross grained
"coarse" is a conventional antonym for "fine".
> + * sis->lock. But cluster and cluster lock isn't available for HDD,
> + * so sis->lock will be instead for them.
> + */
> static inline struct swap_cluster_info *lock_cluster_or_swap_info(
> struct swap_info_struct *si,
> unsigned long offset)
What I already knew was: there are two locks. We use one sometimes and
the other at other times.
What I don't know is why there are two locks, and the heuristics why we
choose between them. This comment doesn't help explain the things I
don't know.
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