From: Yu Zhao <yuzhao@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Stephen Rothwell" <sfr@rothwell.id.au>,
Linux-MM <linux-mm@kvack.org>, "Andi Kleen" <ak@linux.intel.com>,
"Aneesh Kumar" <aneesh.kumar@linux.ibm.com>,
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"Konstantin Kharlamov" <Hi-Angel@yandex.ru>,
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"Sofia Trinh" <sofia.trinh@edi.works>,
"Vaibhav Jain" <vaibhav@linux.ibm.com>
Subject: Re: [PATCH v10 05/14] mm: multi-gen LRU: groundwork
Date: Tue, 26 Apr 2022 19:18:21 -0600 [thread overview]
Message-ID: <CAOUHufbMA7VutATpDYZ15JT_WuP9MGL_Vp6q5KFk72OjzRV+qQ@mail.gmail.com> (raw)
In-Reply-To: <20220426164241.99e6a283c371ed75fa5c12a0@linux-foundation.org>
On Tue, Apr 26, 2022 at 5:42 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 26 Apr 2022 16:39:07 -0600 Yu Zhao <yuzhao@google.com> wrote:
>
> > On Mon, Apr 11, 2022 at 8:16 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> > >
> > > On Wed, 6 Apr 2022 21:15:17 -0600 Yu Zhao <yuzhao@google.com> wrote:
> > >
> > > > Evictable pages are divided into multiple generations for each lruvec.
> > > > The youngest generation number is stored in lrugen->max_seq for both
> > > > anon and file types as they are aged on an equal footing. The oldest
> > > > generation numbers are stored in lrugen->min_seq[] separately for anon
> > > > and file types as clean file pages can be evicted regardless of swap
> > > > constraints. These three variables are monotonically increasing.
> > > >
> > > > ...
> > > >
> > > > +static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
> > >
> > > There's a lot of function inlining here. Fortunately the compiler will
> > > ignore it all, because some of it looks wrong. Please review (and
> > > remeasure!). If inlining is reqlly justified, use __always_inline, and
> > > document the reasons for doing so.
> >
> > I totally expect modern compilers to make better decisions than I do.
> > And personally, I'd never use __always_inline; instead, I'd strongly
> > recommend FDO/LTO.
>
> My (badly expressed) point is that there's a lot of inlining of large
> functions here.
>
> For example, lru_gen_add_folio() is huge and has 4(?) call sites. This
> may well produce slower code due to the icache footprint.
>
> Experiment: moving lru_gen_del_folio() into mm/vmscan.c shrinks that
> file's .text from 80612 bytes to 78956.
>
> I tend to think that out-of-line regular old C functions should be the
> default and that the code should be inlined only when a clear benefit
> is demonstrable, or has at least been seriously thought about.
I can move those functions to vmscan.c if you think it would improve
performance. I don't have a strong opinion here -- I was able to
measure the bloat but not the performance impact.
> > > > --- a/mm/Kconfig
> > > > +++ b/mm/Kconfig
> > > > @@ -909,6 +909,14 @@ config ANON_VMA_NAME
> > > > area from being merged with adjacent virtual memory areas due to the
> > > > difference in their name.
> > > >
> > > > +config LRU_GEN
> > > > + bool "Multi-Gen LRU"
> > > > + depends on MMU
> > > > + # the following options can use up the spare bits in page flags
> > > > + depends on !MAXSMP && (64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP)
> > > > + help
> > > > + A high performance LRU implementation to overcommit memory.
> > > > +
> > > > source "mm/damon/Kconfig"
> > >
> > > This is a problem. I had to jump through hoops just to be able to
> > > compile-test this. Turns out I had to figure out how to disable
> > > MAXSMP.
> > >
> > > Can we please figure out a way to ensure that more testers are at least
> > > compile testing this? Allnoconfig, defconfig, allyesconfig, allmodconfig.
> > >
> > > Also, I suggest that we actually make MGLRU the default while in linux-next.
> >
> > The !MAXSMP is to work around [1], which I haven't had the time to
> > fix. That BUILD_BUG_ON() shouldn't assert sizeof(struct page) == 64
> > since the true size depends on WANT_PAGE_VIRTUAL as well as
> > LAST_CPUPID_NOT_IN_PAGE_FLAGS. My plan is here [2].
> >
> > [1] https://lore.kernel.org/r/20190905154603.10349-4-aneesh.kumar@linux.ibm.com/
> > [2] https://lore.kernel.org/r/Ygl1Gf+ATBuI%2Fm2q@google.com/
>
> OK, thanks. This is fairly urgent for -next and -rc inclusion. If
> practically nobody is compiling the feature then practically nobody is
> testing it. Let's come up with a way to improves the expected coverage
> by a lot.
Let me just remove !MAXSMP, since I wasn't able to reproduce this
build error [1] anymore.
[1] https://lore.kernel.org/r/1792f0b2e29.d72f70c9807100.8179330337708563324@xanmod.org/
next prev parent reply other threads:[~2022-04-27 1:19 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 3:15 [PATCH v10 00/14] Multi-Gen LRU Framework Yu Zhao
2022-04-07 3:15 ` [PATCH v10 01/14] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2022-04-07 3:15 ` [PATCH v10 02/14] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2022-04-07 3:15 ` [PATCH v10 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao
2022-04-16 6:48 ` Miaohe Lin
2022-04-07 3:15 ` [PATCH v10 04/14] Revert "include/linux/mm_inline.h: fold __update_lru_size() into its sole caller" Yu Zhao
2022-04-16 6:50 ` Miaohe Lin
2022-04-07 3:15 ` [PATCH v10 05/14] mm: multi-gen LRU: groundwork Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-12 7:06 ` Peter Zijlstra
2022-04-20 0:39 ` Yu Zhao
2022-04-20 20:07 ` Linus Torvalds
2022-04-26 22:39 ` Yu Zhao
2022-04-26 23:42 ` Andrew Morton
2022-04-27 1:18 ` Yu Zhao [this message]
2022-04-27 1:34 ` Andrew Morton
2022-04-07 3:15 ` [PATCH v10 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao
2022-04-14 6:03 ` Barry Song
2022-04-14 20:36 ` Yu Zhao
2022-04-14 21:39 ` Andrew Morton
2022-04-14 22:14 ` Yu Zhao
2022-04-15 10:15 ` Barry Song
2022-04-15 20:17 ` Yu Zhao
2022-04-15 10:26 ` Barry Song
2022-04-15 20:18 ` Yu Zhao
2022-04-14 11:47 ` Chen Wandun
2022-04-14 20:53 ` Yu Zhao
2022-04-15 2:23 ` Chen Wandun
2022-04-15 5:25 ` Yu Zhao
2022-04-15 6:31 ` Chen Wandun
2022-04-15 6:44 ` Yu Zhao
2022-04-15 9:27 ` Chen Wandun
2022-04-18 9:58 ` Barry Song
2022-04-19 0:53 ` Yu Zhao
2022-04-19 4:25 ` Barry Song
2022-04-19 4:36 ` Barry Song
2022-04-19 22:25 ` Yu Zhao
2022-04-19 22:20 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 07/14] mm: multi-gen LRU: exploit locality in rmap Yu Zhao
2022-04-27 4:32 ` Aneesh Kumar K.V
2022-04-27 4:38 ` Yu Zhao
2022-04-27 5:31 ` Aneesh Kumar K V
2022-04-27 6:00 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 08/14] mm: multi-gen LRU: support page table walks Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-12 7:10 ` Peter Zijlstra
2022-04-15 5:30 ` Yu Zhao
2022-04-15 1:14 ` Yu Zhao
2022-04-15 1:56 ` Andrew Morton
2022-04-15 6:25 ` Yu Zhao
2022-04-15 19:15 ` Andrew Morton
2022-04-15 20:11 ` Yu Zhao
2022-04-15 21:32 ` Andrew Morton
2022-04-15 21:36 ` Linus Torvalds
2022-04-15 22:57 ` Yu Zhao
2022-04-15 23:03 ` Linus Torvalds
2022-04-15 23:24 ` [page-reclaim] " Jesse Barnes
2022-04-15 23:31 ` Matthew Wilcox
2022-04-15 23:37 ` Jesse Barnes
2022-04-15 23:49 ` Yu Zhao
2022-04-16 16:32 ` Justin Forbes
2022-04-19 22:32 ` Yu Zhao
2022-04-29 14:10 ` zhong jiang
2022-04-30 8:34 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 09/14] mm: multi-gen LRU: optimize multiple memcgs Yu Zhao
2022-04-07 3:15 ` [PATCH v10 10/14] mm: multi-gen LRU: kill switch Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-26 20:57 ` Yu Zhao
2022-04-26 22:22 ` Andrew Morton
2022-04-27 1:11 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 11/14] mm: multi-gen LRU: thrashing prevention Yu Zhao
2022-04-07 3:15 ` [PATCH v10 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-16 0:03 ` Yu Zhao
2022-04-16 4:20 ` Andrew Morton
2022-04-26 6:59 ` Yu Zhao
2022-04-26 21:30 ` Andrew Morton
2022-04-26 22:15 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 13/14] mm: multi-gen LRU: admin guide Yu Zhao
2022-04-07 12:41 ` Bagas Sanjaya
2022-04-07 12:51 ` Jonathan Corbet
2022-04-12 2:16 ` Andrew Morton
2022-04-16 2:22 ` Yu Zhao
2022-04-07 3:15 ` [PATCH v10 14/14] mm: multi-gen LRU: design doc Yu Zhao
2022-04-07 11:39 ` Huang Shijie
2022-04-07 12:41 ` Bagas Sanjaya
2022-04-07 12:52 ` Jonathan Corbet
2022-04-08 4:48 ` Bagas Sanjaya
2022-04-12 2:16 ` Andrew Morton
2022-04-26 7:42 ` Yu Zhao
2022-04-07 3:24 ` [PATCH v10 00/14] Multi-Gen LRU Framework Yu Zhao
2022-04-07 8:31 ` Stephen Rothwell
2022-04-07 9:08 ` Yu Zhao
2022-04-07 9:41 ` Yu Zhao
2022-04-07 12:13 ` Stephen Rothwell
2022-04-08 2:08 ` Yu Zhao
2022-04-12 2:15 ` Andrew Morton
2022-04-14 5:06 ` Andrew Morton
2022-04-20 0:50 ` Yu Zhao
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