From: Nadav Amit <namit@vmware.com>
To: Chih-En Lin <shiyn.lin@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Qi Zheng <zhengqi.arch@bytedance.com>,
David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
Iurii Zaikin <yzaikin@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
William Kucharski <william.kucharski@oracle.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Peter Xu <peterx@redhat.com>,
Suren Baghdasaryan <surenb@google.com>,
Arnd Bergmann <arnd@arndb.de>,
Tong Tiangen <tongtiangen@huawei.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Li kunyu <kunyu@nfschina.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Minchan Kim <minchan@kernel.org>, Yang Shi <shy828301@gmail.com>,
Song Liu <song@kernel.org>, Miaohe Lin <linmiaohe@huawei.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Fenghua Yu <fenghua.yu@intel.com>,
Dinglan Peng <peng301@purdue.edu>,
Pedro Fonseca <pfonseca@purdue.edu>,
Jim Huang <jserv@ccns.ncku.edu.tw>,
Huichun Feng <foxhoundsk.tw@gmail.com>
Subject: Re: [RFC PATCH v2 2/9] mm: pgtable: Add sysctl to enable COW PTE
Date: Tue, 27 Sep 2022 17:27:45 +0000 [thread overview]
Message-ID: <8632896B-35D1-4B8F-8A7F-275DEEBCB962@vmware.com> (raw)
In-Reply-To: <20220927162957.270460-3-shiyn.lin@gmail.com>
On Sep 27, 2022, at 9:29 AM, Chih-En Lin <shiyn.lin@gmail.com> wrote:
> Add a new sysctl vm.cow_pte to set MMF_COW_PTE_READY flag for enabling
> copy-on-write (COW) to the PTE page table during the next time of fork.
>
> Since it has a time gap between using the sysctl to enable the COW PTE
> and doing the fork, we use two states to determine the task that wants
> to do COW PTE or already doing it.
I don’t get why it is needed in general and certainly why sysctl controls
this behavior.
IIUC, it sounds that you want prctl and not sysctl for such control. But
clearly you think that this control is needed because there is a tradeoff.
Please explain the tradeoff and how users are expected to make a decision
whether to turn the flag or not.
next prev parent reply other threads:[~2022-09-27 17:27 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-27 16:29 [RFC PATCH v2 0/9] Introduce Copy-On-Write to Page Table Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 1/9] mm: Add new mm flags for Copy-On-Write PTE table Chih-En Lin
2022-09-27 17:23 ` Nadav Amit
2022-09-27 17:36 ` Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 2/9] mm: pgtable: Add sysctl to enable COW PTE Chih-En Lin
2022-09-27 17:27 ` Nadav Amit [this message]
2022-09-27 18:05 ` Chih-En Lin
2022-09-27 21:22 ` John Hubbard
2022-09-28 8:36 ` Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 3/9] mm, pgtable: Add ownership to PTE table Chih-En Lin
2022-09-27 17:30 ` Nadav Amit
2022-09-27 18:23 ` Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 4/9] mm: Add COW PTE fallback functions Chih-En Lin
2022-09-27 17:51 ` Nadav Amit
2022-09-27 19:00 ` Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 5/9] mm, pgtable: Add a refcount to PTE table Chih-En Lin
2022-09-27 17:59 ` Nadav Amit
2022-09-27 19:07 ` Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 6/9] mm, pgtable: Add COW_PTE_OWNER_EXCLUSIVE flag Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 7/9] mm: Add the break COW PTE handler Chih-En Lin
2022-09-27 18:15 ` Nadav Amit
2022-09-27 19:23 ` Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 8/9] mm: Handle COW PTE with reclaim algorithm Chih-En Lin
2022-09-27 16:29 ` [RFC PATCH v2 9/9] mm: Introduce Copy-On-Write PTE table Chih-En Lin
2022-09-27 18:38 ` Nadav Amit
2022-09-27 19:53 ` Chih-En Lin
2022-09-27 21:26 ` John Hubbard
2022-09-28 8:52 ` Chih-En Lin
2022-09-28 14:03 ` David Hildenbrand
2022-09-29 13:38 ` Chih-En Lin
2022-09-29 13:49 ` Chih-En Lin
2022-09-29 17:24 ` David Hildenbrand
2022-09-29 18:29 ` Chih-En Lin
2022-09-29 18:38 ` David Hildenbrand
2022-09-29 18:57 ` Chih-En Lin
2022-09-29 19:00 ` David Hildenbrand
2022-09-29 18:40 ` Nadav Amit
2022-09-29 19:02 ` Chih-En Lin
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