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Thu, 22 Jan 2026 17:07:24 -0800 (PST) MIME-Version: 1.0 References: <20260110042249.31960-1-jianyuew@nvidia.com> <20260122114242.72139-1-wujianyue000@gmail.com> <20260122091351.0cc1afd5d419fafa1d98b32f@linux-foundation.org> In-Reply-To: From: Jianyue Wu Date: Fri, 23 Jan 2026 09:07:13 +0800 X-Gm-Features: AZwV_Qgio7l1Tz4KXAornt7DlVb5tk0mkWvHJrP1iqEKzzaPj3CCOYauPVz9-7A Message-ID: Subject: Re: [PATCH v3] mm: optimize stat output for 11% sys time reduce To: Shakeel Butt Cc: Andrew Morton , hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, inwardvessel@gmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 65ge4yso41in5kcs4xhji3ijhufx4yzw X-Rspamd-Queue-Id: 83C7020002 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1769130446-218125 X-HE-Meta: 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 uSAnVNM8 m3RsAKB0xe8R9XuWL0rOiI1J/iIHF/rz1gDD6VDkCBfvRlwv2QvDObQFHxA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.004266, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jan 23, 2026 at 5:12=E2=80=AFAM Shakeel Butt wrote: > > On Thu, Jan 22, 2026 at 09:13:51AM -0800, Andrew Morton wrote: > > On Thu, 22 Jan 2026 19:42:42 +0800 Jianyue Wu = wrote: > > So the tl;dr here is "vfprintf() is slow". > > > > It's quite a large change, although not a complex one. > > > > Do we need to change so much? Would some subset of these changes > > provide most of the benefit? > > > > It does rather uglify things so there's a risk that helpful people will > > send "cleanups" which switch back to using *printf*. Explanatory code > > comments would help prevent that but we'd need a lot of them. > > > > I dunno, what do people think? Does the benefit justify the change? > > It does come with significant benefit but there is no urgency and we can > definitely decrease the ugliness. JP told me he has some ideas to > improve this. > > Andrew, let's skip this patch for the upcoming merge window and you can > drop it from mm-tree if it is a burden. > Agree. This touches a lot of code and increases complexity, which is a significant downside. If there are ideas to improve it, that=E2=80=99d be great. I=E2=80=99m OK with dropping it for the upcoming merge window, and drop it = if it is a burden.