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Wed, 24 Mar 2021 12:04:46 -0700 (PDT) Received: from [2620:15c:17:3:4192:718f:4827:be5] ([2620:15c:17:3:4192:718f:4827:be5]) by smtp.gmail.com with ESMTPSA id y24sm3225118pfn.213.2021.03.24.12.04.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 12:04:45 -0700 (PDT) Date: Wed, 24 Mar 2021 12:04:45 -0700 (PDT) From: David Rientjes To: "Matthew Wilcox (Oracle)" cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Christoph Lameter , Pekka Enberg , Joonsoo Kim , Vlastimil Babka , Uladzislau Rezki , Nicholas Piggin Subject: Re: [PATCH v2 3/4] mm/vmalloc: Use kvmalloc to allocate the table of pages In-Reply-To: <20210324150518.2734402-4-willy@infradead.org> Message-ID: <9e3d5e8a-4e47-d29a-8474-925036d8e5b@google.com> References: <20210324150518.2734402-1-willy@infradead.org> <20210324150518.2734402-4-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Stat-Signature: ftydpg35z8drkz7ac6mhydzdqtraahzh X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E7B7B6000109 Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf25; identity=mailfrom; envelope-from=""; helo=mail-pg1-f169.google.com; client-ip=209.85.215.169 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616612686-758980 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 Wed, 24 Mar 2021, Matthew Wilcox (Oracle) wrote: > If we're trying to allocate 4MB of memory, the table will be 8KiB in size > (1024 pointers * 8 bytes per pointer), which can usually be satisfied > by a kmalloc (which is significantly faster). Instead of changing this > open-coded implementation, just use kvmalloc(). > > This improves the allocation speed of vmalloc(4MB) by approximately > 5% in our benchmark. It's still dominated by the 1024 calls to > alloc_pages_node(), which will be the subject of a later patch. > > Signed-off-by: Matthew Wilcox (Oracle) Acked-by: David Rientjes