From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Linux-MM <linux-mm@kvack.org>,
Linux-FSDevel <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH 7/8] mm, Remove cold parameter from free_hot_cold_page*
Date: Thu, 19 Oct 2017 15:12:33 +0200 [thread overview]
Message-ID: <9e260f57-b871-81bd-66ee-b08fff949c7c@suse.cz> (raw)
In-Reply-To: <20171018075952.10627-8-mgorman@techsingularity.net>
On 10/18/2017 09:59 AM, Mel Gorman wrote:
> Most callers users of free_hot_cold_page claim the pages being released are
> cache hot. The exception is the page reclaim paths where it is likely that
> enough pages will be freed in the near future that the per-cpu lists are
> going to be recycled and the cache hotness information is lost.
Maybe it would make sense for reclaim to skip pcplists? (out of scope of
this series, of course).
> As no one
> really cares about the hotness of pages being released to the allocator,
> just ditch the parameter.
>
> The APIs are renamed to indicate that it's no longer about hot/cold pages. It
> should also be less confusing as there are subtle differences between them.
> __free_pages drops a reference and frees a page when the refcount reaches
> zero. free_hot_cold_page handled pages whose refcount was already zero
> which is non-obvious from the name. free_unref_page should be more obvious.
>
> No performance impact is expected as the overhead is marginal. The parameter
> is removed simply because it is a bit stupid to have a useless parameter
> copied everywhere.
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
A comment below, though.
...
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 167e163cf733..13582efc57a0 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2590,7 +2590,7 @@ void mark_free_pages(struct zone *zone)
> }
> #endif /* CONFIG_PM */
>
> -static bool free_hot_cold_page_prepare(struct page *page, unsigned long pfn)
> +static bool free_unref_page_prepare(struct page *page, unsigned long pfn)
> {
> int migratetype;
>
> @@ -2602,8 +2602,7 @@ static bool free_hot_cold_page_prepare(struct page *page, unsigned long pfn)
> return true;
> }
>
> -static void free_hot_cold_page_commit(struct page *page, unsigned long pfn,
> - bool cold)
> +static void free_unref_page_commit(struct page *page, unsigned long pfn)
> {
> struct zone *zone = page_zone(page);
> struct per_cpu_pages *pcp;
> @@ -2628,10 +2627,7 @@ static void free_hot_cold_page_commit(struct page *page, unsigned long pfn,
> }
>
> pcp = &this_cpu_ptr(zone->pageset)->pcp;
> - if (!cold)
> - list_add(&page->lru, &pcp->lists[migratetype]);
> - else
> - list_add_tail(&page->lru, &pcp->lists[migratetype]);
> + list_add_tail(&page->lru, &pcp->lists[migratetype]);
Did you intentionally use the cold version here? Patch 8/8 uses the hot
version in __rmqueue_pcplist() and that makes more sense to me. It
should be either negligible or better, not worse.
> pcp->count++;
> if (pcp->count >= pcp->high) {
> unsigned long batch = READ_ONCE(pcp->batch);
next prev parent reply other threads:[~2017-10-19 13:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-18 7:59 [PATCH 0/8] Follow-up for speed up page cache truncation v2 Mel Gorman
2017-10-18 7:59 ` [PATCH 1/8] mm, page_alloc: Enable/disable IRQs once when freeing a list of pages Mel Gorman
2017-10-18 9:02 ` Vlastimil Babka
2017-10-18 10:15 ` Mel Gorman
2017-10-18 7:59 ` [PATCH 2/8] mm, truncate: Do not check mapping for every page being truncated Mel Gorman
2017-10-19 8:11 ` Jan Kara
2017-10-18 7:59 ` [PATCH 3/8] mm, truncate: Remove all exceptional entries from pagevec under one lock Mel Gorman
2017-10-18 7:59 ` [PATCH 4/8] mm: Only drain per-cpu pagevecs once per pagevec usage Mel Gorman
2017-10-19 9:12 ` Vlastimil Babka
2017-10-19 9:33 ` Mel Gorman
2017-10-19 13:21 ` Vlastimil Babka
2017-10-18 7:59 ` [PATCH 5/8] mm, pagevec: Remove cold parameter for pagevecs Mel Gorman
2017-10-19 9:24 ` Vlastimil Babka
2017-10-18 7:59 ` [PATCH 6/8] mm: Remove cold parameter for release_pages Mel Gorman
2017-10-19 9:26 ` Vlastimil Babka
2017-10-18 7:59 ` [PATCH 7/8] mm, Remove cold parameter from free_hot_cold_page* Mel Gorman
2017-10-19 13:12 ` Vlastimil Babka [this message]
2017-10-19 15:43 ` Mel Gorman
2017-10-18 7:59 ` [PATCH 8/8] mm: Remove __GFP_COLD Mel Gorman
2017-10-19 13:18 ` Vlastimil Babka
2017-10-19 13:42 ` Vlastimil Babka
2017-10-19 14:32 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2017-10-12 9:30 [PATCH 0/8] Follow-up for speed up page cache truncation Mel Gorman
2017-10-12 9:31 ` [PATCH 7/8] mm, Remove cold parameter from free_hot_cold_page* Mel Gorman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9e260f57-b871-81bd-66ee-b08fff949c7c@suse.cz \
--to=vbabka@suse.cz \
--cc=ak@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=dave.hansen@intel.com \
--cc=david@fromorbit.com \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).