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Fri, 28 Apr 2023 09:17:55 -0700 (PDT) MIME-Version: 1.0 References: <20230427153345.451d86681f9c6775ea579e5a@linux-foundation.org> In-Reply-To: From: Suren Baghdasaryan Date: Fri, 28 Apr 2023 09:17:44 -0700 Message-ID: Subject: Re: [GIT PULL] MM updates for 6.4-rc1 To: Linus Torvalds Cc: Andrew Morton , mm-commits@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lorenzo Stoakes , Vlastimil Babka Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: AACAD80008 X-Stat-Signature: uufwyqf6uksbbyyq9kc4xf3gmcmd5ybg X-HE-Tag: 1682698676-570017 X-HE-Meta: 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 OXPClod0 O3ydbIksE/2FWCTwfGcvJ1ucpbJMWTSro893ar3eaTUOfGmBbV6Q72BV+svw7+1WComQv5KkgRzxc8xObOfrczIsIp2Tekns8aOVZ8R3jy6QGuEAenFn0Pi+vU6WyTdTzs5rGOSRsb7zNAOsn2JlSmJMFtrGU/CHfPYFyI9F3Lg2p6F2M4EYqu6SsC55bMIwJicDl7/HTYhEfIfKGygYGoXhblMpeSjBxVo1wqGY3yJ+juc0rYAg5mwSYMECz8shPq+crb3xM4w5/RarJ62KzD+o0eUGFroMqMhzvsO1fb2kKKk21UvtlRcqeWw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 28, 2023 at 9:14=E2=80=AFAM Suren Baghdasaryan wrote: > > On Fri, Apr 28, 2023 at 9:08=E2=80=AFAM Linus Torvalds > wrote: > > > > On Fri, Apr 28, 2023 at 9:03=E2=80=AFAM Suren Baghdasaryan wrote: > > > > > > I wanted these stats enabled by default to be able to identify > > > possible pathological cases and to also let users disable them if the= y > > > can't tolerate even a small overhead in the pagefault path. Should I > > > document this reasoning for the config option? > > > > You should document what the stats actually count (at a high enough > > level for a user to understand), and why anybody would want to keep > > them on. > > > > Honestly, 99% of the time, these are things that *developers* think > > they might want, but that nobody else will ever ever use. > > > > Really, ask yourself if a normal user would ever look at them? > > > > Now, ask yourself whether this might be something that a cloud > > provider would want to look at to gather statistics. > > > > And if it's the latter case, then it should be "default n", because > > the default should be for the people who DO NOT KNOW, AND DO NOT CARE. > > > > The cloud provider will be using a custom config anyway. The default > > is irrelevant for that use. The use that *matters* is literally the > > clueless end user who I bet will never look at these numbers, and will > > never be asked for them. > > Ok, sounds like this should be 'default n'. I'll prepare a patch. Thanks! Should I send a replacement patch for "mm: introduce per-VMA lock statistics" or a followup patch fixing it? > > > > > Linus