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[2003:cb:c705:800:1a88:f98a:d223:c454]) by smtp.gmail.com with ESMTPSA id e7-20020a056000120700b00241dd5de644sm31418655wrx.97.2023.01.18.06.30.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Jan 2023 06:30:19 -0800 (PST) Message-ID: <305a756b-b977-8d08-fd7c-d41ec5dfe5d1@redhat.com> Date: Wed, 18 Jan 2023 15:30:18 +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, 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 References: <202212300915147801864@zte.com.cn> From: David Hildenbrand Organization: Red Hat In-Reply-To: <202212300915147801864@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: rspam05 X-Rspamd-Queue-Id: 24C5A16003D X-Stat-Signature: qds77hk3kojqhftcfkd7sigmmfweiyw5 X-Rspam-User: X-HE-Tag: 1674052227-291110 X-HE-Meta: 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 e7ujx9Uj Ca26lbofFbCcSYtrxtxMSZMzfhtbrGrCCUBdAPqhuRWYd+v6j+EHMDztsnTvjKAlikLTGPgvFUpB3nkrF05JOkvYsmLCC0jm0pR9s0O+y9cXHjrAToQqV3BpXGzXlRgOjMa+5RyCdegu4oCqJUZiqGfd/XtMOtEzrQ7G/ZME6z3/gFVA/k3j0JRTjtfDvnVQECNqXf1Y4x5eWbFWEM/okRsDNHFCxJ/R63uFS3K/GbDdYvEOLOolJWZfG3teruz4GZdMFBG3YWce8ChGNjUxI0VrEMg== 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 30.12.22 02:15, yang.yang29@zte.com.cn wrote: > From: xu xin > > As pages_sharing and pages_shared don't include the number of zero pages > merged by KSM, we cannot know how many pages are zero pages placed by KSM > when enabling use_zero_pages, which leads to KSM not being transparent with > all actual merged pages by KSM. In the early days of use_zero_pages, > zero-pages was unable to get unshared by the ways like MADV_UNMERGEABLE so > it's hard to count how many times one of those zeropages was then unmerged. > > But now, unsharing KSM-placed zero page accurately has been achieved, so we > can easily count both how many times a page full of zeroes was merged with > zero-page and how many times one of those pages was then unmerged. and so, > it helps to estimate memory demands when each and every shared page could > get unshared. > > So we add zero_pages_sharing under /sys/kernel/mm/ksm/ to show the number > of all zero pages placed by KSM. > > Signed-off-by: xu xin > Cc: Claudio Imbrenda > Cc: David Hildenbrand > Cc: Xuexin Jiang > Reviewed-by: Xiaokai Ran > Reviewed-by: Yang Yang > > v4->v5: > fix warning mm/ksm.c:3238:9: warning: no previous prototype for > 'zero_pages_sharing_show' [-Wmissing-prototypes]. > --- > mm/ksm.c | 19 +++++++++++++++++-- > 1 file changed, 17 insertions(+), 2 deletions(-) > > 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? IOW, if someone triggers MADV_DONTNEED on such a zeropage, the counter will not get updated, correct? -- Thanks, David / dhildenb