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[2003:cb:c74c:b400:5c8b:a0b2:f57e:e1cd]) by smtp.gmail.com with ESMTPSA id o2-20020a056000010200b002ca864b807csm10836709wrx.0.2023.05.23.03.01.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 May 2023 03:01:38 -0700 (PDT) Message-ID: <04d3ffe2-46ce-db30-8f1b-cb05cd21d328@redhat.com> Date: Tue, 23 May 2023 12:01:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v8 5/6] ksm: update the calculation of KSM profit To: Yang Yang , akpm@linux-foundation.org Cc: imbrenda@linux.ibm.com, jiang.xuexin@zte.com.cn, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ran.xiaokai@zte.com.cn, xu.xin.sc@gmail.com, xu.xin16@zte.com.cn, Stefan Roesch References: <202305221842587200002@zte.com.cn> <20230522105402.4225-1-yang.yang29@zte.com.cn> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230522105402.4225-1-yang.yang29@zte.com.cn> 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-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 442DA100028 X-Stat-Signature: h8hx4a9jb5dzhaebpag7szezpkixszze X-HE-Tag: 1684836101-348743 X-HE-Meta: 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 eIGFsGu/ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.002100, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 22.05.23 12:54, Yang Yang wrote: > From: xu xin > I suggest changing the subject to "ksm: consider KSM-placed zeropages when calculating KSM profit" > When use_zero_pages is enabled, the calculation of ksm profit is not > correct because ksm zero pages is not counted in. So update the > calculation of KSM profit including the documentation. > > Signed-off-by: xu xin > Cc: Xiaokai Ran > Cc: Yang Yang > Cc: Jiang Xuexin > Cc: Claudio Imbrenda > Cc: David Hildenbrand > --- > Documentation/admin-guide/mm/ksm.rst | 18 +++++++++++------- > mm/ksm.c | 2 +- > 2 files changed, 12 insertions(+), 8 deletions(-) > > diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst > index 019dc40a0d3c..dde7c152f0ae 100644 > --- a/Documentation/admin-guide/mm/ksm.rst > +++ b/Documentation/admin-guide/mm/ksm.rst > @@ -204,21 +204,25 @@ several times, which are unprofitable memory consumed. > 1) How to determine whether KSM save memory or consume memory in system-wide > range? Here is a simple approximate calculation for reference:: > > - general_profit =~ pages_sharing * sizeof(page) - (all_rmap_items) * > + general_profit =~ ksm_saved_pages * sizeof(page) - (all_rmap_items) * > sizeof(rmap_item); > > - where all_rmap_items can be easily obtained by summing ``pages_sharing``, > - ``pages_shared``, ``pages_unshared`` and ``pages_volatile``. > + where ksm_saved_pages equals to the sum of ``pages_sharing`` + > + ``ksm_zero_pages`` of the system, and all_rmap_items can be easily > + obtained by summing ``pages_sharing``, ``pages_shared``, ``pages_unshared`` > + and ``pages_volatile``. > > 2) The KSM profit inner a single process can be similarly obtained by the > following approximate calculation:: > > - process_profit =~ ksm_merging_pages * sizeof(page) - > + process_profit =~ ksm_saved_pages * sizeof(page) - > ksm_rmap_items * sizeof(rmap_item). > > - where ksm_merging_pages is shown under the directory ``/proc//``, > - and ksm_rmap_items is shown in ``/proc//ksm_stat``. The process profit > - is also shown in ``/proc//ksm_stat`` as ksm_process_profit. > + where ksm_saved_pages equals to the sum of ``ksm_merging_pages`` and > + ``ksm_zero_pages``, both of which are shown under the directory > + ``/proc//ksm_stat``, and ksm_rmap_items is alos shown in s/alos/also/ > + ``/proc//ksm_stat``. The process profit is also shown in > + ``/proc//ksm_stat`` as ksm_process_profit. > > From the perspective of application, a high ratio of ``ksm_rmap_items`` to > ``ksm_merging_pages`` means a bad madvise-applied policy, so developers or > diff --git a/mm/ksm.c b/mm/ksm.c > index 4e510f5c5938..d23a240c2519 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -3085,7 +3085,7 @@ static void wait_while_offlining(void) > #ifdef CONFIG_PROC_FS > long ksm_process_profit(struct mm_struct *mm) > { > - return mm->ksm_merging_pages * PAGE_SIZE - > + return (long)(mm->ksm_merging_pages + mm->ksm_zero_pages) * PAGE_SIZE - > mm->ksm_rmap_items * sizeof(struct ksm_rmap_item); > } > #endif /* CONFIG_PROC_FS */ Apart from that LGTM. CCing Stefan R. -- Thanks, David / dhildenb