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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1666681815; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=L4lUHvQEMKR3V8SAeCBrP3BHLGEPzUD0h8eSeuTa0g0=; b=LKrUuJiSreMoY+tKEMbwSI72RM12OFTZdm7IK6q3O7G5z3rPQdSMTGautGCkdWY2TepW9+ +mIWwfiClSQEivjImn8gq/nXc38pTqRp+xZrmM+BDk91g8L1AOUvFfvCkN/C4WNNVc+zhC 1JCn47nCwuWbirLRgB/L9dCA3vpaCOs= From: Yajun Deng To: rppt@kernel.org, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yajun Deng Subject: [PATCH v2] memblock: don't run loop in memblock_add_range() twice Date: Tue, 25 Oct 2022 15:09:43 +0800 Message-Id: <20221025070943.363578-1-yajun.deng@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666681817; a=rsa-sha256; cv=none; b=XNMHxnCg4HThGQdmddIFyLGy1Xp+a5Kb64dLkmKJKeZv95tGraa/GBiROGqm/fTx3vDk0Y cJMGiciO6bHfv9plqFel7G7VYNB86hBi4/k9YXJpwAL2SdTFa50QV+O2yMbzN+7QrPzwqB NmsTW7ta+N4EKNESDgLe6Gs8mf2vrnE= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LKrUuJiS; spf=pass (imf27.hostedemail.com: domain of yajun.deng@linux.dev designates 188.165.223.204 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666681817; 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-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=L4lUHvQEMKR3V8SAeCBrP3BHLGEPzUD0h8eSeuTa0g0=; b=HIi6W+Jj5Xy8LYUwu/iDhAW6UVrp7QDa5yq8jwbPS61rgqeZ5NVxYDvHWZ1qbKGTVpiMm+ GYF6s4kuqG4OTKPxp95qKyQN2X2+xwk6dQDiV2KVBlItadgrmGN2mN4q4AH8IuE3djUGPM P9Ac+FVQqj9nSj/qAE92Ztj676lcWc4= X-Rspamd-Queue-Id: 2955140015 X-Rspam-User: Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LKrUuJiS; spf=pass (imf27.hostedemail.com: domain of yajun.deng@linux.dev designates 188.165.223.204 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Rspamd-Server: rspam04 X-Stat-Signature: i339u5sgzjt7mf3zqsrqyrsusztxh49z X-HE-Tag: 1666681816-687443 X-Bogosity: Ham, tests=bogofilter, spamicity=0.004083, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: There is no need round twice in memblock_add_range(). We can call memblock_double_array() to extend the size if type->cnt greater or equal to type->max before memblock_insert_region(); otherwise, we can insert the new region directly. v2: - Add a comment when the allocation is required. Signed-off-by: Yajun Deng --- mm/memblock.c | 69 ++++++++++++++++++--------------------------------- 1 file changed, 24 insertions(+), 45 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index 511d4783dcf1..602fa8ee9b71 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -578,10 +578,10 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, phys_addr_t base, phys_addr_t size, int nid, enum memblock_flags flags) { - bool insert = false; phys_addr_t obase = base; phys_addr_t end = base + memblock_cap_size(base, &size); - int idx, nr_new; + unsigned long ocnt = type->cnt; + int idx; struct memblock_region *rgn; if (!size) @@ -598,25 +598,6 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, return 0; } - /* - * The worst case is when new range overlaps all existing regions, - * then we'll need type->cnt + 1 empty regions in @type. So if - * type->cnt * 2 + 1 is less than type->max, we know - * that there is enough empty regions in @type, and we can insert - * regions directly. - */ - if (type->cnt * 2 + 1 < type->max) - insert = true; - -repeat: - /* - * The following is executed twice. Once with %false @insert and - * then with %true. The first counts the number of regions needed - * to accommodate the new area. The second actually inserts them. - */ - base = obase; - nr_new = 0; - for_each_memblock_type(idx, type, rgn) { phys_addr_t rbase = rgn->base; phys_addr_t rend = rbase + rgn->size; @@ -634,11 +615,18 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, WARN_ON(nid != memblock_get_region_node(rgn)); #endif WARN_ON(flags != rgn->flags); - nr_new++; - if (insert) - memblock_insert_region(type, idx++, base, - rbase - base, nid, - flags); + + /* + * if type->cnt greater or equal to type->max, + * resize array; otherwise, insert directly. + */ + if ((type->cnt >= type->max) && + memblock_double_array(type, obase, size)) + return -ENOMEM; + + memblock_insert_region(type, idx++, base, + rbase - base, nid, + flags); } /* area below @rend is dealt with, forget about it */ base = min(rend, end); @@ -646,29 +634,20 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, /* insert the remaining portion */ if (base < end) { - nr_new++; - if (insert) - memblock_insert_region(type, idx, base, end - base, - nid, flags); + if ((type->cnt >= type->max) && + memblock_double_array(type, obase, size)) + return -ENOMEM; + + memblock_insert_region(type, idx, base, end - base, + nid, flags); } - if (!nr_new) + if (ocnt == type->cnt) return 0; - /* - * If this was the first round, resize array and repeat for actual - * insertions; otherwise, merge and return. - */ - if (!insert) { - while (type->cnt + nr_new > type->max) - if (memblock_double_array(type, obase, size) < 0) - return -ENOMEM; - insert = true; - goto repeat; - } else { - memblock_merge_regions(type); - return 0; - } + memblock_merge_regions(type); + + return 0; } /** -- 2.25.1