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d=linux-foundation.org; s=korg; t=1692381790; bh=GcHOZuE+yu2rWZVOxdHvFqURHbfpZ1mp7n9HpH+zdzU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VznVWNicvACp1njnOOXedvuJgDQqYM+Q9dBLYk37vX0JeFjqG6ZVjdI8nItAMS9UY nhZdm9XF5qcAUERZcp5KcupokYXEDxkWf1RsS947vdeWju2XqX0ukQykAthnVJppKe 8TgKWHdI1jbiHSy7EtytTr+TA3eRqkxxhEZIr7ZM= Date: Fri, 18 Aug 2023 11:03:09 -0700 From: Andrew Morton To: Sidhartha Kumar Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, songmuchun@bytedance.com, mike.kravetz@oracle.com, willy@infradead.org Subject: Re: [PATCH v6] mm/filemap: remove hugetlb special casing in filemap.c Message-Id: <20230818110309.e9debd8b988cb8ca4a1019be@linux-foundation.org> In-Reply-To: <20230817181836.103744-1-sidhartha.kumar@oracle.com> References: <20230817181836.103744-1-sidhartha.kumar@oracle.com> X-Mailer: Sylpheed 3.8.0beta1 (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-Queue-Id: 2C4E21C0019 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: qkykk1gsr1d9hmo31jsmbp4mqzti35tm X-HE-Tag: 1692381791-301683 X-HE-Meta: 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 UCWdcYUN u+xNN2CMWPyD+w9P0WdPt9hAC2n7ROlCnTM3wgYsk+lXns/EE0ongXcDrIL39jiCkLEkwC2dV7vdFMmQI4dPcAbyU9FZz6z69ozzi8XPOi2NfOm1zUE5bkIEbjLWat4NeWW6Lixvg91Qcm7tMFSLR48NgqHUjRZJ4i0DMN2XcJidfjb0V80syv4cYpH/BW5wPBY46fHJAimIIrdQjdj4TWTEvCi8hkAuvJLlIH7791jcQdJ9dxiksyOq36Wy3fNEwYcAjHcLOjek5QXhvXC+ucp4k81LHpohrDK97kZ3sLrtEYaNJjBulha33Rg== 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 Thu, 17 Aug 2023 11:18:36 -0700 Sidhartha Kumar wrote: > Perf was used to check the performance differences after the patch. Overall > the performance is similar to mainline with a very small larger overhead that > occurs in __filemap_add_folio() and hugetlb_add_to_page_cache(). This is because > of the larger overhead that occurs in xa_load() and xa_store() as the > xarray is now using more entries to store hugetlb folios in the page cache. So... why merge the patch? To save 40 lines of code? I mean, if a patch which added 40 lines yielded a "very small" reduction in overhead, we'd probably merge it! Or is there some wider reason for this which the changelog omitted?