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[2003:cb:c705:6d00:5870:9639:1c17:8162]) by smtp.gmail.com with ESMTPSA id b15-20020a5d550f000000b002c55ebe37ddsm1164222wrv.115.2023.02.13.04.55.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Feb 2023 04:55:23 -0800 (PST) Message-ID: <2b62898c-2f39-bc0d-e801-20b5efe90dfd@redhat.com> Date: Mon, 13 Feb 2023 13:55:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v5 3/6] ksm: count all zero pages placed by KSM To: yang.yang29@zte.com.cn Cc: akpm@linux-foundation.org, 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 References: <202302092001576896055@zte.com.cn> From: David Hildenbrand Organization: Red Hat In-Reply-To: <202302092001576896055@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-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8FAA612001C X-Rspam-User: X-Stat-Signature: pqddpc1nxbtxdsebkugiontdoy66q47e X-HE-Tag: 1676292927-900567 X-HE-Meta: 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 gqbvmYLV 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 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 09.02.23 13:01, yang.yang29@zte.com.cn wrote: >>> diff --git a/mm/ksm.c b/mm/ksm.c >>> index 652c088f9786..72c0722be280 100644 >>> --- a/mm/ksm.c >>> +++ b/mm/ksm.c >>> @@ -276,6 +276,9 @@ static unsigned int zero_checksum __read_mostly; >>> /* Whether to merge empty (zeroed) pages with actual zero pages */ >>> static bool ksm_use_zero_pages __read_mostly; >>> >>> +/* The number of zero pages placed by KSM use_zero_pages */ >>> +static unsigned long ksm_zero_pages_sharing; >> >> Does this count how many zero pages are currently placed or how many >> rmap items with ZERO_PAGE_FLAG are in the system? > > Yes, it counts how many ksm zero pages are currently placed. and we use > rmap items with ZERO_PAGE_FLAG to record these zero page, similar to > ksm_pages_sharing and ksm_pages_shared which are recorded by the rmap_items > with STABLE_FLAG. > >> >> IOW, if someone triggers MADV_DONTNEED on such a zeropage, the counter >> will not get updated, correct? > > Well, the counter can get updated as someone triggers MADV_DONTNEED on such > a zeropage. You might write a simple code to test it. Interesting, I'll have a look how that will be triggered. -- Thanks, David / dhildenb