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[2003:cb:c70e:4f00:87ba:e9e9:3821:677b]) by smtp.gmail.com with ESMTPSA id p8-20020adfcc88000000b002c55b0e6ef1sm16095335wrj.4.2023.03.02.06.55.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 02 Mar 2023 06:55:06 -0800 (PST) Message-ID: <15cf14e3-946e-269b-f98d-004c395524ae@redhat.com> Date: Thu, 2 Mar 2023 15:55:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v2 0/5] batched remove rmap in try_to_unmap_one() To: Matthew Wilcox Cc: "Yin, Fengwei" , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "mike.kravetz@oracle.com" , "sidhartha.kumar@oracle.com" , "naoya.horiguchi@nec.com" , "chu, jane" References: <20230228122308.2972219-1-fengwei.yin@intel.com> <20230228122823.eba4f0fa5f7f436a2f8b3a3b@linux-foundation.org> <19263da54b9818332620345bbed69e8ded241e00.camel@intel.com> <604c372c-e474-14a7-dd80-c5197f12564d@redhat.com> <1c6c9d3e-3a7e-4d07-7c7c-9b7c01bcdac6@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: 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-Stat-Signature: i59uiyonc6rwnuiexxjb4xek41muh9xw X-Rspam-User: X-Rspamd-Queue-Id: A7BBFC0015 X-Rspamd-Server: rspam06 X-HE-Tag: 1677768911-546207 X-HE-Meta: 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 UUTwaYy1 Lq6xxvJPj06iCw0gJqyCh9U7Tp28zaOUz7kV6IBz4xmy2Y4J+8H5TYLjL1csYkT1hb1MEEQbmHKh4ZjuXPK0z8bgSEoEiuhyzSUdNC+uDZ5nPy4FAcPoXV9WrA7Gle1grDYiut52P0WdtttH++4TUeBSZKS6KDMTNXiEuG37S7WDWtlPtAfWLGVPP8X1Ad5wpM28tNxletS4D8NqgW2KhBfuFklzxymR6XOvoFUnK6rB0ftzkOim51jUSGA8Yb+2g+tU5wls1a8DES7mJ4jSYzVtEXVshzlDgjg/D7o2KM53iDEYE05NkHpHtE5pu3nwPnE04YHI/c5tEvqUyG+ZSCQKNpFucVsJj4PtBUjY703rjyrn/chFBAnHoklu6RhZlhxpCxjnXlR4sOefyGNDhtupJRIr7wnqtvu1tMNZkFbjvDw8JD8jGbOx1YCrNEVsOjSb4z4gXMnUzD/JRgBA4g0rCJ0tVx4omKeMMqzyqy8GTZuY= 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 02.03.23 15:33, Matthew Wilcox wrote: > On Thu, Mar 02, 2023 at 03:23:46PM +0100, David Hildenbrand wrote: >> If no workload/benchmark is affected (or simply corner cases where nobody >> cares about performance), I hope you understand that it's hard to argue why >> we should care about such an optimization then. > > In order to solve the mapcount problem, we're going to want to unmap > the entire folio in one call, instead of unmapping each page in it > individually and checking each time whether there are any remaining > pages from this folio still mapped. Okay, thanks. That should better be added to the cover letter, ideally with more details on the mapcount goal and how this patch set will helps in that regard. So far the cover letter only talks about eventual performance gains. -- Thanks, David / dhildenb