From: "Huang, Ying" <ying.huang@intel.com>
To: Barry Song <21cnbao@gmail.com>, Matthew Wilcox <willy@infradead.org>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
ryan.roberts@arm.com, chengming.zhou@linux.dev,
chrisl@kernel.org, david@redhat.com, hannes@cmpxchg.org,
kasong@tencent.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mhocko@suse.com,
nphamcs@gmail.com, shy828301@gmail.com, steven.price@arm.com,
surenb@google.com, wangkefeng.wang@huawei.com,
willy@infradead.org, xiang@kernel.org, yosryahmed@google.com,
yuzhao@google.com, Chuanhua Han <hanchuanhua@oppo.com>,
Barry Song <v-songbaohua@oppo.com>
Subject: Re: [RFC PATCH v3 5/5] mm: support large folios swapin as a whole
Date: Fri, 15 Mar 2024 16:41:37 +0800 [thread overview]
Message-ID: <87wmq3yji6.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <20240304081348.197341-6-21cnbao@gmail.com> (Barry Song's message of "Mon, 4 Mar 2024 21:13:48 +1300")
Barry Song <21cnbao@gmail.com> writes:
> From: Chuanhua Han <hanchuanhua@oppo.com>
>
> On an embedded system like Android, more than half of anon memory is
> actually in swap devices such as zRAM. For example, while an app is
> switched to background, its most memory might be swapped-out.
>
> Now we have mTHP features, unfortunately, if we don't support large folios
> swap-in, once those large folios are swapped-out, we immediately lose the
> performance gain we can get through large folios and hardware optimization
> such as CONT-PTE.
>
> This patch brings up mTHP swap-in support. Right now, we limit mTHP swap-in
> to those contiguous swaps which were likely swapped out from mTHP as a
> whole.
>
> Meanwhile, the current implementation only covers the SWAP_SYCHRONOUS
> case. It doesn't support swapin_readahead as large folios yet since this
> kind of shared memory is much less than memory mapped by single process.
In contrast, I still think that it's better to start with normal swap-in
path, then expand to SWAP_SYCHRONOUS case.
In normal swap-in path, we can take advantage of swap readahead
information to determine the swapped-in large folio order. That is, if
the return value of swapin_nr_pages() > 1, then we can try to allocate
and swapin a large folio.
To do that, we need to track whether the sub-pages are accessed. I
guess we need that information for large file folio readahead too.
Hi, Matthew,
Can you help us on tracking whether the sub-pages of a readahead large
folio has been accessed?
> Right now, we are re-faulting large folios which are still in swapcache as a
> whole, this can effectively decrease extra loops and early-exitings which we
> have increased in arch_swap_restore() while supporting MTE restore for folios
> rather than page. On the other hand, it can also decrease do_swap_page as
> PTEs used to be set one by one even we hit a large folio in swapcache.
>
--
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2024-03-15 8:43 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 8:13 [RFC PATCH v3 0/5] mm: support large folios swap-in Barry Song
2024-03-04 8:13 ` [RFC PATCH v3 1/5] arm64: mm: swap: support THP_SWAP on hardware with MTE Barry Song
2024-03-11 16:55 ` Ryan Roberts
2024-03-21 8:42 ` Barry Song
2024-03-21 10:31 ` Ryan Roberts
2024-03-21 10:43 ` Barry Song
2024-03-22 2:51 ` Barry Song
2024-03-22 7:41 ` Barry Song
2024-03-22 10:19 ` Ryan Roberts
2024-03-23 2:15 ` Chris Li
2024-03-23 3:50 ` Barry Song
2024-03-04 8:13 ` [RFC PATCH v3 2/5] mm: swap: introduce swap_nr_free() for batched swap_free() Barry Song
2024-03-11 18:51 ` Ryan Roberts
2024-03-14 13:12 ` Chuanhua Han
2024-03-14 13:43 ` Ryan Roberts
2024-03-15 8:34 ` Chuanhua Han
2024-03-15 10:57 ` Ryan Roberts
2024-03-18 1:28 ` Chuanhua Han
2024-03-04 8:13 ` [RFC PATCH v3 3/5] mm: swap: make should_try_to_free_swap() support large-folio Barry Song
2024-03-12 12:34 ` Ryan Roberts
2024-03-13 2:21 ` Chuanhua Han
2024-03-13 9:09 ` Ryan Roberts
2024-03-13 9:24 ` Chuanhua Han
2024-03-04 8:13 ` [RFC PATCH v3 4/5] mm: swap: introduce swapcache_prepare_nr and swapcache_clear_nr for large folios swap-in Barry Song
2024-03-12 15:35 ` Ryan Roberts
2024-03-18 22:35 ` Barry Song
2024-03-04 8:13 ` [RFC PATCH v3 5/5] mm: support large folios swapin as a whole Barry Song
2024-03-12 16:33 ` Ryan Roberts
2024-03-14 12:56 ` Chuanhua Han
2024-03-14 13:57 ` Ryan Roberts
2024-03-14 20:43 ` Barry Song
2024-03-15 10:59 ` Ryan Roberts
2024-03-15 1:16 ` Chuanhua Han
2024-03-15 8:41 ` Huang, Ying [this message]
2024-03-15 8:54 ` Barry Song
2024-03-15 9:15 ` Huang, Ying
2024-03-15 10:01 ` Barry Song
2024-03-15 12:06 ` Ryan Roberts
2024-03-17 6:11 ` Barry Song
2024-03-18 1:52 ` Huang, Ying
2024-03-18 2:41 ` Barry Song
2024-03-18 16:45 ` Ryan Roberts
2024-03-19 6:27 ` Barry Song
2024-03-19 9:05 ` Ryan Roberts
2024-03-21 9:22 ` Barry Song
2024-03-21 11:13 ` Ryan Roberts
2024-03-19 9:20 ` Huang, Ying
2024-03-19 12:19 ` Ryan Roberts
2024-03-20 2:18 ` Huang, Ying
2024-03-20 2:47 ` Barry Song
2024-03-20 6:20 ` Huang, Ying
2024-03-20 18:38 ` Barry Song
2024-03-21 4:23 ` Huang, Ying
2024-03-21 5:12 ` Barry Song
2024-03-21 10:20 ` Barry Song
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