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Tue, 2 Jun 2020 04:48:16 +0000 (UTC) X-HE-Tag: toy23_2b07098045d13 X-Filterd-Recvd-Size: 3764 Received: from hqnvemgate24.nvidia.com (hqnvemgate24.nvidia.com [216.228.121.143]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Jun 2020 04:48:15 +0000 (UTC) Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 01 Jun 2020 21:46:38 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 01 Jun 2020 21:48:14 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 01 Jun 2020 21:48:14 -0700 Received: from [10.2.56.10] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 2 Jun 2020 04:48:09 +0000 Subject: Re: [PATCH] mm/vmstat: Add events for PMD based THP migration without split To: Anshuman Khandual , Daniel Jordan CC: , , Naoya Horiguchi , Zi Yan , Andrew Morton , References: <1590118444-21601-1-git-send-email-anshuman.khandual@arm.com> <20200601165736.qw5kwwknxltk7bv6@ca-dmjordan1.us.oracle.com> <0a936ec7-f44f-1d72-915f-f5758d25fd72@nvidia.com> <1e71d815-5359-3ebe-5d2b-5a3b54b63b51@arm.com> X-Nvconfidentiality: public From: John Hubbard Message-ID: <274be3bf-2206-5e98-8114-1d91fac472c9@nvidia.com> Date: Mon, 1 Jun 2020 21:48:09 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1 MIME-Version: 1.0 In-Reply-To: <1e71d815-5359-3ebe-5d2b-5a3b54b63b51@arm.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1591073198; bh=u6lPTpjCI+gaUy3MTSH/RHMFz1vUb7fWJf9p4QDoBpE=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=jhu/uGxUYNr5WDT8xucP55UuqM1volhBWfQ0lBWdtIuuZdfrAA/Z+q5I3/BUmzOZ5 FdxVLonV+v6bmCPw2shM8XVJP8T/wyHN948EA5e9FhCqlvpzRLH6vVNTex6f5jLkg+ 8c+dLGaySGxQd7DA/lmfMek9SxuVWlrwcoSVBISJP+pqFLAMHAq0t/uV3vZSORAcWW fdbVOOb+uh2SvWbWim3WND6Y54GBAcRFH5SSgz+VnPFLsvYpurwEeoqA7pSrOreUbJ RW5VIIvTM5OswNTiZDNgQ0r7xvhN5NVC2xLXGFcrGaEimlrF9kV8+Hu7PwQMEtDogX DTJbUb9TM1yrg== X-Rspamd-Queue-Id: 1238B37604 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 2020-06-01 21:20, Anshuman Khandual wrote: ... >> also important: maybe this patch should also be tracking other causes >> of THP PMD migration failure, in order to get a truer accounting of the >> situation. I hope one of the experts here can weigh in on that... > Is there any other failure reasons which are only specific to THP migration. > Else, adding stats about generic migration failure reasons will just blur > the overall understanding about THP migration successes and failure cases > that results in splitting. > Thinking about that: we do have PGMIGRATE_SUCCESS and PGMIGRATE_FAIL, so I suppose comparing those numbers with the new THP_PMD_MIGRATION_SUCCESS and THP_PMD_MIGRATION_FAILURE events should cover it. However, the fact that this is under discussion hints at the need for a bit of documentation help. What do you think about adding some notes about all of this to, say, Documentation/vm/page_migration.rst ? thanks, -- John Hubbard NVIDIA