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Groups > linux.kernel > #1626900
| Path | csiph.com!aioe.org!news.servidellagleba.it!bofh.it!news.nic.it!robomod |
|---|---|
| From | "Huang\, Ying" <ying.huang@intel.com> |
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out |
| Date | Thu, 20 Apr 2017 02:50:01 +0200 |
| Message-ID | <ty8sh-1SW-3@gated-at.bofh.it> (permalink) |
| References | <txRUu-lm-9@gated-at.bofh.it> <txRUv-lm-33@gated-at.bofh.it> <ty0bo-5gm-1@gated-at.bofh.it> |
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| Sender | robomod@news.nic.it |
| List-ID | <linux-kernel.vger.kernel.org> |
| X-Mailing-List | linux-kernel@vger.kernel.org |
| Approved | robomod@news.nic.it |
| Lines | 58 |
| Organization | linux.* mail to news gateway |
| X-Original-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> |
| X-Original-Date | Thu, 20 Apr 2017 08:43:12 +0800 |
| X-Original-Message-ID | <87inlzrjrz.fsf@yhuang-dev.intel.com> |
| X-Original-References | <20170419070625.19776-1-ying.huang@intel.com> <20170419070625.19776-2-ying.huang@intel.com> <20170419155252.GA3376@cmpxchg.org> |
| X-Original-Sender | linux-kernel-owner@vger.kernel.org |
| Xref | csiph.com linux.kernel:1626900 |
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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
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[PATCH -mm -v9 0/3] THP swap: Delay splitting THP during swapping out "Huang, Ying" <ying.huang@intel.com> - 2017-04-19 09:10 +0200
[PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out "Huang, Ying" <ying.huang@intel.com> - 2017-04-19 09:10 +0200
Re: [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out Johannes Weiner <hannes@cmpxchg.org> - 2017-04-19 18:00 +0200
Re: [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out "Huang\, Ying" <ying.huang@intel.com> - 2017-04-20 02:50 +0200
Re: [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out Johannes Weiner <hannes@cmpxchg.org> - 2017-04-21 16:10 +0200
Re: [PATCH -mm -v9 1/3] mm, THP, swap: Delay splitting THP during swap out "Huang\, Ying" <ying.huang@intel.com> - 2017-04-22 02:10 +0200
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