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Rao" Subject: Re: [PATCH 09/13] mm/powerpc: Redefine pXd_huge() with pXd_leaf() Message-ID: References: <20240313214719.253873-10-peterx@redhat.com> <7b7d6ce1-4a3f-4392-951d-a9bd146c954c@csgroup.eu> <1f6ad500-3ff7-44d4-8223-067bd2ed9ffe@csgroup.eu> <20240318161519.GA5825@nvidia.com> <20240319232656.GC159172@nvidia.com> <7ca8f19e-7517-404a-b7bb-92ac516d87c8@csgroup.eu> <2e632389-eb4e-42af-adee-36d5ba6c3d0f@csgroup.eu> MIME-Version: 1.0 In-Reply-To: <2e632389-eb4e-42af-adee-36d5ba6c3d0f@csgroup.eu> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: wa1dbhebtn9d8wwtm54z356ihmajnwha X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2B27C18000C X-HE-Tag: 1710966272-309952 X-HE-Meta: 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 YPQ/xdtF bAR7EspEUUFf8jOLM485oiAXvjCmxvlDAYQR28FbbcR/ek+TsF3EhSbw8Az/3HVihpCfA+VnaY1UV3+UoiDcyGmtFjD+lvbW5+5aaCCWKzR3QqUdKGfJ0OfKdYDPPLMQeQYRZB+32LF3CL2CSJg0sXUEUeoNTsIckwCptfCvb4PxYhSewb+/z63E6/g== 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: List-Subscribe: List-Unsubscribe: On Wed, Mar 20, 2024 at 05:40:39PM +0000, Christophe Leroy wrote: > > > Le 20/03/2024 à 17:09, Peter Xu a écrit : > > On Wed, Mar 20, 2024 at 06:16:43AM +0000, Christophe Leroy wrote: > >> At the first place that was to get a close fit between hardware > >> pagetable topology and linux pagetable topology. But obviously we > >> already stepped back for 512k pages, so let's go one more step aside and > >> do similar with 8M pages. > >> > >> I'll give it a try and see how it goes. > > > > So you're talking about 8M only for 8xx, am I right? > > Yes I am. > > > > > There seem to be other PowerPC systems use hugepd. Is it possible that we > > convert all hugepd into cont_pte form? > > Indeed. > > Seems like we have hugepd for book3s/64 and for nohash. > > For book3s I don't know, may Aneesh can answer. > > For nohash I think it should be possible because TLB misses are handled > by software. Even the e6500 which has a hardware tablewalk falls back on > software walk when it is a hugepage IIUC. It'll be great if I can get some answer here, and then I know the path for hugepd in general. I don't want to add any new code into core mm to something destined to fade away soon. One option for me is I can check a macro of hugepd existance, so all new code will only work when hugepd is not supported on such arch. However that'll start to make some PowerPC systems special (which I still tried hard to avoid, if that wasn't proved in the past..), meanwhile we'll also need to keep some generic-mm paths (that I can already remove along with the new code) only for these hugepd systems. But it's still okay to me, it'll be just a matter of when to drop those codes, sooner or later. Thanks, -- Peter Xu