From: "Huang\, Ying" <ying.huang@intel.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huang\, Ying" <ying.huang@intel.com>,
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: Thu, 20 Apr 2017 08:43:12 +0800 [thread overview]
Message-ID: <87inlzrjrz.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <20170419155252.GA3376@cmpxchg.org> (Johannes Weiner's message of "Wed, 19 Apr 2017 11:52:52 -0400")
Hi, Johannes,
Johannes Weiner <hannes@cmpxchg.org> writes:
> 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.
I just found there are unlikely() encloses PageTransHuge() in the
original add_to_swap(), so I just follow the original style. But I
don't think they make much sense too. Will remove them in the next
version.
> Also please mention changes like these in the changelog next time.
Sorry and will do that in the future.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2017-04-20 0:43 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
2017-04-20 0:43 ` Huang, Ying [this message]
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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