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b=MR6HUthqtyJKDRNHZntDDIi19c/cnLf5fyQfQMd40D8lXvjU9KGrJ4Dtpbdc1mv8o NhlI4zcuTW0PURTt5HS+mxm/u6FOUrwU1BYL2hZLQqBva9zK3sdUnH7QiiQnfLiqHT AHV2SoXuWAF+k9LngDfeT7coeFX4pdYE+sl8f+kM= Date: Thu, 26 Dec 2024 16:23:15 -0800 From: Andrew Morton To: Suren Baghdasaryan Cc: kent.overstreet@linux.dev, yuzhao@google.com, 00107082@163.com, quic_zhenhuah@quicinc.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 2/2] alloc_tag: skip pgalloc_tag_swap if profiling is disabled Message-Id: <20241226162315.cbf088cb28fe897bfe1b075b@linux-foundation.org> In-Reply-To: References: <20241226211639.1357704-1-surenb@google.com> <20241226211639.1357704-2-surenb@google.com> <20241226150127.73d1b2a08cf31dac1a900c1e@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: ybwe9jyx6x5pd61a7b6sigkmq4m4myib X-Rspam-User: X-Rspamd-Queue-Id: CC1CFC000A X-Rspamd-Server: rspam08 X-HE-Tag: 1735258978-592566 X-HE-Meta: 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 vOyPkwSM 7k8tHuRwJZZ3qB2xgJbNwyIA/zdJXmUFLO12o0ORC/STSqVkNDeR+wAo8XJLsILLV7v87YFk1cZkXRCOhKjKpxOEGghl0M/0NKRK/9aC3qBlPF19rdMURgU53/5G/SSdwvDUKj/B1LgcrdECNaZfO2zehLConIkeFxCVtFb//rDJrR4YJikqV6NRKwCvNspilgbuDdwIjpxicWGnnUlvaQgqxcfdKj55hOGXZOwkJ7W/XNnbglvtds1gnuKFpKRkjx98SjqZeHaQLyG9aDR6bo2oFr/zF+W7ggCidb5x6QACuhjSmVvceDyiHEcB3ie/ZJnLTJQ/SKtHgAcxtuN8wLSos13U0Q2nzFuQsZ1XvwZoQPfwEtipTYSN01DkNeVTM/blf6qxhCpZKIu7aQYP1NP/7kPaHCnwcziMhWpDW0wnKnqU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, 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 Thu, 26 Dec 2024 15:07:39 -0800 Suren Baghdasaryan wrote: > On Thu, Dec 26, 2024 at 3:01 PM Andrew Morton wrote: > > > > On Thu, 26 Dec 2024 13:16:39 -0800 Suren Baghdasaryan wrote: > > > > > When memory allocation profiling is disabled, there is no need to swap > > > allocation tags during migration. Skip it to avoid unnecessary overhead. > > > > > > Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") > > > Signed-off-by: Suren Baghdasaryan > > > Cc: stable@vger.kernel.org > > > > Are these changes worth backporting? Some indication of how much > > difference the patches make would help people understand why we're > > proposing a backport. > > The first patch ("alloc_tag: avoid current->alloc_tag manipulations > when profiling is disabled") I think is worth backporting. It > eliminates about half of the regression for slab allocations when > profiling is disabled. um, what regression? The changelog makes no mention of this. Please send along a suitable Reported-by: and Closes: and a summary of the benefits so that people can actually see what this patch does, and why.