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[2003:cb:c74b:3400:ec51:7a3a:274e:cbee]) by smtp.gmail.com with ESMTPSA id w4-20020a5d5444000000b0031f3b04e7cdsm12205388wrv.109.2023.09.18.04.28.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Sep 2023 04:28:39 -0700 (PDT) Message-ID: Date: Mon, 18 Sep 2023 13:28:38 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v1 3/4] mm/ksm: document smart scan mode To: Stefan Roesch , kernel-team@fb.com Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, riel@surriel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20230912175228.952039-1-shr@devkernel.io> <20230912175228.952039-4-shr@devkernel.io> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230912175228.952039-4-shr@devkernel.io> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 200BA4000E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 3ae3caayexe649b5ac7hkmr4bhwgqrx5 X-HE-Tag: 1695036522-993707 X-HE-Meta: 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 HZoGbvA/ U4Z/1i48MNZS2t24PDHxCO8mb+NodsQ0nQF+8Iq1NDS3aHEX4uHi/USuhWEyj/5ThDuhuR4vmbnYJZ02IHGx7n9lvjFQdrOxF2PTwi+7CsuLU2P8fwAeeIp7+5oa8PbDzMJURMaqIF/qgG0RvSbzeMlly9svWUe52VT5AE3Wlk9V5jiVeZq/qNnexi9eahn5s8cn6U3tvBSUF7eaM5YdfrChw/tSW9hLrFb/I0N3Xy6u3cE7wlGQRYUsa18Ddwk1s4h5uVn8VVIFA+AFW6JlBrd7WS7y6ZOyNcYiU0vTXKLXaJbcX6RTnfVj2LlxUx9ZnZnWk7Swr2GO8PpflO1dgGnjbGJvb9dcpNVF4ez3DLTiQWFg4M26tgEg+TwJxHJn5AMgZ/M5AwI733n3h4HUwkDXIpQ== 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 12.09.23 19:52, Stefan Roesch wrote: > This adds documentation for the smart scan mode of KSM. > > Signed-off-by: Stefan Roesch > --- > Documentation/admin-guide/mm/ksm.rst | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst > index 776f244bdae4..1762219baf51 100644 > --- a/Documentation/admin-guide/mm/ksm.rst > +++ b/Documentation/admin-guide/mm/ksm.rst > @@ -155,6 +155,15 @@ stable_node_chains_prune_millisecs > scan. It's a noop if not a single KSM page hit the > ``max_page_sharing`` yet. > > +smart_scan > + By default KSM checks every candidate page for each scan. It does > + not take into account historic information. When smart scan is > + enabled, pages that have previously not been de-duplicated get > + skipped. How often these pages are skipped depends on how often > + de-duplication has already been tried and failed. By default this > + optimization is disabled. The ``pages_skipped`` metric shows how > + effetive the setting is. > + > The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``: > > general_profit Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb