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b=XkL+wqeXq+QtvK3TnB/VUUBwmFtPbvn8/HrJSnhIUrVJxgDrS52Pcz5QoXkXJgpQQ Cl6a9ul1dmOxu2ZxUYoijuyZFBzmClMdWVTczEfJWa+tOBCkQZox2KoOBRpAfOtMxN 82oJtsjJEektBFMs0cMUXM6zuL7oblIYkmSVrLsE= Date: Tue, 25 Jun 2024 15:33:38 -0700 From: Andrew Morton To: David Hildenbrand Cc: Matthew Wilcox , Sergey Senozhatsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mike Rapoport , Minchan Kim , Hyeonggon Yoo <42.hyeyoo@gmail.com> Subject: Re: [PATCH v2 3/6] mm/zsmalloc: use a proper page type Message-Id: <20240625153338.8a4d049857d59e692a0d31e6@linux-foundation.org> In-Reply-To: <345161ac-3b42-48aa-ab3d-3b183316479a@redhat.com> References: <20240529111904.2069608-1-david@redhat.com> <20240529111904.2069608-4-david@redhat.com> <20240530050123.GA8400@google.com> <345161ac-3b42-48aa-ab3d-3b183316479a@redhat.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 977FDC0011 X-Stat-Signature: zf78og1jqbqtbs1y7q5nunzwy4o45yn4 X-Rspam-User: X-HE-Tag: 1719354824-477579 X-HE-Meta: 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 oiN3+3qT 9GeoqgMjOC+NYukGl0LT8qKAr+76ldChBRA+OcYCtmruOeKLHfGbmFGYCx+gPmJZKZ/7ceImi/Y8yoR6Y0l4p8vEh9KA8GboQT7ByVb3dXQum472VR2fZC9Ew6PucT5mF+NiN3GxEp36ELLovu8yKNU5kKV1932fW5VWdPJQwpjOo2RwTzesJrXSx6Qh7fJ87skEVkMH2R0iEqeuxLsL2NnspMvY2H/vjpDJxzJr/pTlw51W3R6LMN4oagyEBgB/JVIjfdB1ISRedUg4LNx4Ye241+N8nTFqa5VBwblNECEm3eJdU7eyVDbkbZuth+rwm4M1ePPu7rioYH+1ahi2sMefXMbTHzJyMcIyzlwWFC5153k93r5txvTSbaQ== 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 Fri, 31 May 2024 16:32:04 +0200 David Hildenbrand wrote: > On 31.05.24 16:27, Matthew Wilcox wrote: > > On Thu, May 30, 2024 at 02:01:23PM +0900, Sergey Senozhatsky wrote: > > 1409: 83 c0 01 add $0x1,%eax > > if (mapcount < PAGE_MAPCOUNT_RESERVE + 1) > > 140c: 83 f8 81 cmp $0xffffff81,%eax > > 140f: 7d 63 jge 1474 > 4> > > if (folio_test_hugetlb(folio)) > > 1411: 80 7b 33 84 cmpb $0x84,0x33(%rbx) > > 1415: 74 4e je 1465 > > > > so we go from "mov, and, cmp, je" to just "cmpb, je", which must surely > > be faster to execute as well as being more compact in the I$ (6 bytes vs 15). > > > > Anyway, not tested but this is the patch I used to generate the above. > > More for comment than application. > > Right, it's likely very similar to my previous proposal to use 8 bit > (uint8_t) for the type. > > https://lore.kernel.org/all/00ba1dff-7c05-46e8-b0d9-a78ac1cfc198@redhat.com/ > > I would prefer if we would do that separately; unless someone is able to > raise why we care about zram + 256KiB that much right now. (claim: we don't) > iow, "this is ok for now", yes? I'd like to push this into mm-"stable" later this week. Speak now or forever hold your pieces.