From: Hillf Danton <hdanton@sina.com>
To: Yu Zhao <yuzhao@google.com>
Cc: Will Deacon <will@kernel.org>, Linux-MM <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 01/11] mm: x86, arm64: add arch_has_hw_pte_young()
Date: Sun, 10 Oct 2021 16:59:07 +0800 [thread overview]
Message-ID: <20211010085907.1284-1-hdanton@sina.com> (raw)
In-Reply-To: <CAOUHufbysyPZFZDOaGn+FwVojy-krCZR--7dd0qkWqKL+s9S_Q@mail.gmail.com>
On Thu, 19 Aug 2021 15:23:02 -0600 Yu Zhao wrote:
>On Thu, Aug 19, 2021 at 3:19 AM Will Deacon <will@kernel.org> wrote:
>>
>> How accurate does this need to be? Heterogeneous (big/little) systems are
>> very common on arm64, so the existing code enables hardware access flag
>> unconditionally on CPUs that support it, meaning we could end up running
>> on a system where some CPUs have hardware update and others do not.
>>
>> With your change, we only enable hardware access flag if _all_ CPUs support
>> it (and furthermore, we prevent late onlining of CPUs without the feature
>> if was detected at boot). This sacrifices a lot of flexibility, particularly
>> if we end up tackling CPU errata in this area in future, and it's not clear
>> that it's really required for what you're trying to do.
>
>It doesn't need to be accurate but then my question is how helpful it
>is if it's not accurate.
Alternatively to make the issue simpler, spin without arm64 included given
that it will be revisited once MGLRU lands in the mainline tree.
Hillf
next prev parent reply other threads:[~2021-10-10 8:59 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-18 6:30 [PATCH v4 00/11] Multigenerational LRU Framework Yu Zhao
2021-08-18 6:30 ` [PATCH v4 01/11] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2021-08-19 9:19 ` Will Deacon
2021-08-19 21:23 ` Yu Zhao
2021-10-10 8:59 ` Hillf Danton [this message]
2021-08-18 6:30 ` [PATCH v4 02/11] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2021-08-18 6:30 ` [PATCH v4 03/11] mm/vmscan.c: refactor shrink_node() Yu Zhao
2021-08-18 6:31 ` [PATCH v4 04/11] mm: multigenerational lru: groundwork Yu Zhao
2021-08-18 6:31 ` [PATCH v4 05/11] mm: multigenerational lru: protection Yu Zhao
2021-08-18 6:31 ` [PATCH v4 06/11] mm: multigenerational lru: mm_struct list Yu Zhao
2021-08-18 6:31 ` [PATCH v4 07/11] mm: multigenerational lru: aging Yu Zhao
2021-08-18 6:31 ` [PATCH v4 08/11] mm: multigenerational lru: eviction Yu Zhao
2021-08-18 6:31 ` [PATCH v4 09/11] mm: multigenerational lru: user interface Yu Zhao
2021-08-18 6:31 ` [PATCH v4 10/11] mm: multigenerational lru: Kconfig Yu Zhao
2021-08-18 6:31 ` [PATCH v4 11/11] mm: multigenerational lru: documentation Yu Zhao
2021-10-09 5:43 ` [PATCH v4 00/11] Multigenerational LRU Framework bot
2021-10-21 19:41 ` bot
2021-11-02 0:20 ` bot
2021-11-09 2:13 ` bot
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