From: Shaohua Li <shli@fb.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<Kernel-team@fb.com>, <mhocko@suse.com>, <minchan@kernel.org>,
<hughd@google.com>, <riel@redhat.com>,
<mgorman@techsingularity.net>, <akpm@linux-foundation.org>
Subject: Re: [PATCH V3 2/7] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list
Date: Thu, 16 Feb 2017 16:35:25 -0800 [thread overview]
Message-ID: <20170217003524.GA95440@shli-mbp.local> (raw)
In-Reply-To: <20170216175253.GB20791@cmpxchg.org>
On Thu, Feb 16, 2017 at 12:52:53PM -0500, Johannes Weiner wrote:
> On Tue, Feb 14, 2017 at 11:36:08AM -0800, Shaohua Li wrote:
> > @@ -126,4 +126,24 @@ static __always_inline enum lru_list page_lru(struct page *page)
> >
> > #define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
> >
> > +/*
> > + * lazyfree pages are clean anonymous pages. They have SwapBacked flag cleared
> > + * to destinguish normal anonymous pages.
> > + */
> > +static inline void set_page_lazyfree(struct page *page)
> > +{
> > + VM_BUG_ON_PAGE(!PageAnon(page) || !PageSwapBacked(page), page);
> > + ClearPageSwapBacked(page);
> > +}
> > +
> > +static inline void clear_page_lazyfree(struct page *page)
> > +{
> > + VM_BUG_ON_PAGE(!PageAnon(page) || PageSwapBacked(page), page);
> > + SetPageSwapBacked(page);
> > +}
> > +
> > +static inline bool page_is_lazyfree(struct page *page)
> > +{
> > + return PageAnon(page) && !PageSwapBacked(page);
> > +}
>
> Sorry for not getting to v2 in time, but I have to say I strongly
> agree with your first iterations and would much prefer this to be
> open-coded.
>
> IMO this needlessly introduces a new state opaquely called "lazyfree",
> when really that's just anonymous pages that don't need to be swapped
> before reclaim - PageAnon && !PageSwapBacked. Very simple MM concept.
>
> That especially shows when we later combine it with page_is_file_cache
> checks like the next patch does.
>
> The rest of the patch looks good to me.
Thanks! I do agree checking PageSwapBacked is clearer, but Minchan convinced me
because of the accounting issue. Where do you suggest we should put the
accounting to?
Thanks,
Shaohua
next prev parent reply other threads:[~2017-02-17 0:35 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 19:36 [PATCH V3 0/7] mm: fix some MADV_FREE issues Shaohua Li
2017-02-14 19:36 ` [PATCH V3 1/7] mm: don't assume anonymous pages have SwapBacked flag Shaohua Li
2017-02-16 17:39 ` Johannes Weiner
2017-02-14 19:36 ` [PATCH V3 2/7] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list Shaohua Li
2017-02-16 17:52 ` Johannes Weiner
2017-02-17 0:35 ` Shaohua Li [this message]
2017-02-17 16:22 ` Johannes Weiner
2017-02-14 19:36 ` [PATCH V3 3/7] mm: reclaim MADV_FREE pages Shaohua Li
2017-02-16 18:40 ` Johannes Weiner
2017-02-17 0:27 ` Shaohua Li
2017-02-17 5:45 ` Minchan Kim
2017-02-17 16:11 ` Johannes Weiner
2017-02-17 16:01 ` Johannes Weiner
2017-02-17 18:43 ` Shaohua Li
2017-02-17 20:03 ` Johannes Weiner
2017-02-17 5:41 ` Minchan Kim
2017-02-17 9:27 ` Minchan Kim
2017-02-17 16:15 ` Johannes Weiner
2017-02-14 19:36 ` [PATCH V3 4/7] mm: enable MADV_FREE for swapless system Shaohua Li
2017-02-17 16:16 ` Johannes Weiner
2017-02-14 19:36 ` [PATCH V3 5/7] mm: add vmstat account for MADV_FREE pages Shaohua Li
2017-02-14 19:36 ` [PATCH V3 6/7] proc: show MADV_FREE pages info in smaps Shaohua Li
2017-02-14 19:36 ` [PATCH V3 7/7] mm: add a separate RSS for MADV_FREE pages Shaohua Li
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