From: Johannes Weiner <hannes@cmpxchg.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrea Arcangeli <aarcange@redhat.com>,
Ebru Akagunduz <ebru.akagunduz@gmail.com>,
Michal Hocko <mhocko@kernel.org>, Tejun Heo <tj@kernel.org>,
Hugh Dickins <hughd@google.com>, Shaohua Li <shli@kernel.org>,
Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
cgroups@vger.kernel.org
Subject: Re: [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out
Date: Wed, 19 Apr 2017 11:52:52 -0400 [thread overview]
Message-ID: <20170419155252.GA3376@cmpxchg.org> (raw)
In-Reply-To: <20170419070625.19776-2-ying.huang@intel.com>
On Wed, Apr 19, 2017 at 03:06:23PM +0800, Huang, Ying wrote:
> @@ -206,17 +212,34 @@ int add_to_swap(struct page *page, struct list_head *list)
> */
> err = add_to_swap_cache(page, entry,
> __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
> -
> - if (!err) {
> - return 1;
> - } else { /* -ENOMEM radix-tree allocation failure */
> + /* -ENOMEM radix-tree allocation failure */
> + if (err)
> /*
> * add_to_swap_cache() doesn't return -EEXIST, so we can safely
> * clear SWAP_HAS_CACHE flag.
> */
> - swapcache_free(entry);
> - return 0;
> + goto fail_free;
> +
> + if (unlikely(PageTransHuge(page))) {
> + err = split_huge_page_to_list(page, list);
> + if (err) {
> + delete_from_swap_cache(page);
> + return 0;
> + }
> }
> +
> + return 1;
> +
> +fail_free:
> + if (unlikely(PageTransHuge(page)))
> + swapcache_free_cluster(entry);
> + else
> + swapcache_free(entry);
> +fail:
> + if (unlikely(PageTransHuge(page)) &&
> + !split_huge_page_to_list(page, list))
> + goto retry;
May I ask why you added the unlikelies there? Can you generally say
THPs are unlikely in this path? Is the swap-out path so hot that
branch layout is critical? I doubt either is true.
Also please mention changes like these in the changelog next time.
next prev parent reply other threads:[~2017-04-19 15:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-19 7:06 [PATCH -mm -v9 0/3] THP swap: Delay splitting THP during swapping out Huang, Ying
2017-04-19 7:06 ` [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
2017-04-19 15:52 ` Johannes Weiner [this message]
2017-04-20 0:43 ` Huang, Ying
2017-04-21 6:11 ` Balbir Singh
2017-04-21 7:21 ` Huang, Ying
2017-04-21 14:08 ` Johannes Weiner
2017-04-22 0:07 ` Huang, Ying
2017-04-19 7:06 ` [PATCH -mm -v9 2/3] mm, THP, swap: Check whether THP can be split firstly Huang, Ying
2017-04-19 16:13 ` Johannes Weiner
2017-04-20 0:50 ` Huang, Ying
2017-04-20 20:50 ` Johannes Weiner
2017-04-21 0:34 ` Huang, Ying
2017-04-19 7:06 ` [PATCH -mm -v9 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map Huang, Ying
2017-04-19 16:00 ` Johannes Weiner
2017-04-20 0:51 ` Huang, Ying
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