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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Yu Zhao <yuzhao@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andi Kleen <ak@linux.intel.com>,
	Aneesh Kumar <aneesh.kumar@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Hillf Danton <hdanton@sina.com>, Jens Axboe <axboe@kernel.dk>,
	Jesse Barnes <jsbarnes@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Matthew Wilcox <willy@infradead.org>,
	Mel Gorman <mgorman@suse.de>,
	Michael Larabel <Michael@michaellarabel.com>,
	Michal Hocko <mhocko@kernel.org>, Mike Rapoport <rppt@kernel.org>,
	Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>,
	Will Deacon <will@kernel.org>, Ying Huang <ying.huang@intel.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	page-reclaim@google.com,
	"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: [PATCH v8 00/14] Multi-Gen LRU Framework
Date: Tue, 8 Mar 2022 16:06:54 -0800	[thread overview]
Message-ID: <CAHk-=wi5wg=72exwHODJdVtAfqa1e85dGfjGftuhHQ5Z4v-DNA@mail.gmail.com> (raw)
In-Reply-To: <20220308234723.3834941-1-yuzhao@google.com>

On Tue, Mar 8, 2022 at 3:48 PM Yu Zhao <yuzhao@google.com> wrote:
>
> The current page reclaim is too expensive in terms of CPU usage and it
> often makes poor choices about what to evict. This patchset offers an
> alternative solution that is performant, versatile and
> straightforward.

So apart from my complaints about asking users config questions that
simply should not be asked, I really think this just needs to start
getting merged.

We've seen several numbers on the upsides, and I don't think we'll see
any of the downsides until we try it. And I don't think there is any
question that we _shouldn't_ try it, given the numbers posted.

But yeah, I certainly _hope_ that all the benchmarking has been done
with a unified set of config values, and it's not some kind of bogus
"cherry-picked config values for this particular machine" kind of
benchmarking that has been done.

Because that isn't valid benchmarking - comparing some "tuned for this
paeticular machine or load" setup to a default one is just not worth
even setting numbers to, and debases the whole value of posting
results.

                    Linus

WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Yu Zhao <yuzhao@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andi Kleen <ak@linux.intel.com>,
	Aneesh Kumar <aneesh.kumar@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Dave Hansen <dave.hansen@linux.intel.com>,
	Hillf Danton <hdanton@sina.com>,  Jens Axboe <axboe@kernel.dk>,
	Jesse Barnes <jsbarnes@google.com>,
	 Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	 Matthew Wilcox <willy@infradead.org>,
	Mel Gorman <mgorman@suse.de>,
	 Michael Larabel <Michael@michaellarabel.com>,
	Michal Hocko <mhocko@kernel.org>, Mike Rapoport <rppt@kernel.org>,
	Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>,
	 Will Deacon <will@kernel.org>, Ying Huang <ying.huang@intel.com>,
	 Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	 page-reclaim@google.com,
	"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: [PATCH v8 00/14] Multi-Gen LRU Framework
Date: Tue, 8 Mar 2022 16:06:54 -0800	[thread overview]
Message-ID: <CAHk-=wi5wg=72exwHODJdVtAfqa1e85dGfjGftuhHQ5Z4v-DNA@mail.gmail.com> (raw)
In-Reply-To: <20220308234723.3834941-1-yuzhao@google.com>

On Tue, Mar 8, 2022 at 3:48 PM Yu Zhao <yuzhao@google.com> wrote:
>
> The current page reclaim is too expensive in terms of CPU usage and it
> often makes poor choices about what to evict. This patchset offers an
> alternative solution that is performant, versatile and
> straightforward.

So apart from my complaints about asking users config questions that
simply should not be asked, I really think this just needs to start
getting merged.

We've seen several numbers on the upsides, and I don't think we'll see
any of the downsides until we try it. And I don't think there is any
question that we _shouldn't_ try it, given the numbers posted.

But yeah, I certainly _hope_ that all the benchmarking has been done
with a unified set of config values, and it's not some kind of bogus
"cherry-picked config values for this particular machine" kind of
benchmarking that has been done.

Because that isn't valid benchmarking - comparing some "tuned for this
paeticular machine or load" setup to a default one is just not worth
even setting numbers to, and debases the whole value of posting
results.

                    Linus

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-03-09  1:01 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-08 23:47 [PATCH v8 00/14] Multi-Gen LRU Framework Yu Zhao
2022-03-08 23:47 ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 01/14] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 02/14] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 04/14] Revert "include/linux/mm_inline.h: fold __update_lru_size() into its sole caller" Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 05/14] mm: multi-gen LRU: groundwork Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:58   ` Linus Torvalds
2022-03-08 23:58     ` Linus Torvalds
2022-03-08 23:47 ` [PATCH v8 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-09  0:02   ` Linus Torvalds
2022-03-09  0:02     ` Linus Torvalds
2022-03-08 23:47 ` [PATCH v8 07/14] mm: multi-gen LRU: exploit locality in rmap Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 08/14] mm: multi-gen LRU: support page table walks Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 09/14] mm: multi-gen LRU: optimize multiple memcgs Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 10/14] mm: multi-gen LRU: kill switch Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 11/14] mm: multi-gen LRU: thrashing prevention Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 13/14] mm: multi-gen LRU: admin guide Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-08 23:47 ` [PATCH v8 14/14] mm: multi-gen LRU: design doc Yu Zhao
2022-03-08 23:47   ` Yu Zhao
2022-03-09  0:06 ` Linus Torvalds [this message]
2022-03-09  0:06   ` [PATCH v8 00/14] Multi-Gen LRU Framework Linus Torvalds
2022-03-09  0:14   ` Yu Zhao
2022-03-09  0:14     ` Yu Zhao
2022-03-09  0:29     ` Linus Torvalds
2022-03-09  0:29       ` Linus Torvalds

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