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charset=us-ascii Content-Disposition: inline In-Reply-To: <20220609024122.6679-1-tjytimi@163.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655095526; a=rsa-sha256; cv=none; b=bwKuse/sLLNcFYHEUsHjrH1FQLonHYgwZ1ltEcCoYmH74f9zADqk50jsRmdZW/Y1V8bvZm J94yxkB36OUu+sOqirxDc7wQriH5Zl9iWvIBf/Daw9isHlulR/ao9d/6vvDxA5k8iX0Vrt QfNl0DYPXlinJq47/VyEkLSPLF5OMUI= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=g+cruqpI; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655095526; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kWr8XIDrWB8HZjcXSQvenPk1wZO2eZpTABp3q0yfsxQ=; b=0bCwxAEJJ94IfNFpbhJMRPyMXPV9Xp2Fzd0ju/tffBTHxIL3AMEACxfhO8IXTlAA8JFw0e huavDozX53pvrMY0Dkp66qD+f/ywviEmcrxBrJ0PEMW4oE9qEOcYvD7eimHMh+4Epu3tGN sor07ux2IQFPbncQqUswsSY2zv4+1q8= X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 61E572007C X-Stat-Signature: ortqqst7qsjyzzj9d6jg6jwti53o3ghy X-Rspam-User: Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=g+cruqpI; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-HE-Tag: 1655095526-695123 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000007, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jun 09, 2022 at 10:41:22AM +0800, tjytimi wrote: > The worst case is that the new memory range overlaps all existing > regions,which need type->cnt + 1 free area of struct memblock_region. > So if type->cnt + 1 + type->cnt is less than type->max,we can insert > regions directly.And becase of merge operation in the end of function, > tpye->cnt increase slowly for many cases.So this patch can avoid > unnecessary repeat for many cases when add new memory range. > > Signed-off-by: tjytimi > --- > mm/memblock.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/memblock.c b/mm/memblock.c > index e4f03a6e8..243cd7de5 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -602,6 +602,9 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, > base = obase; > nr_new = 0; > > + if (type->cnt<<1 < type->max - 1) > + insert = true; > + Several things here: - cnt * 2 looks clearer than cnt << 1 and the performance difference (if any) is negligible - I think checking that cnt + 1 < max is easier to read - there should be space around operators, i.e. cnt << 1 I'd also appreciate a comment in the code with the explanation similar to the changelog > for_each_memblock_type(idx, type, rgn) { > phys_addr_t rbase = rgn->base; > phys_addr_t rend = rbase + rgn->size; > -- > 2.32.0 > -- Sincerely yours, Mike.