From nobody Fri Dec 19 14:04:59 2025 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 92A7D2577B for ; Sat, 27 Apr 2024 00:37:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714178267; cv=none; b=azwWRG8Da2LcVUd5jqlbW25YFek6pzk4hhGirJuJMM2+mtLm9aYYe/zzheB8hpQH4ESgO1gQGYNVb3cPyDrKxohQ5ZNQIi1hom3B15LJW8PqQsSc0+LYVmdahF35sA8ep/iI3jaK0ejSQR9yaAZfTfsAAL02jMZR4iAMYQFg49o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714178267; c=relaxed/simple; bh=tJK4g+poJ9VBpRehNiwwG1ZwM1nTxzq5jA9+UhY0/zc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GgBcGdFGOHHsEYRpnhJ69VeN807mIMgJiM5VMAHve6EOflh18aImACHgChxzHjgeQR846Gi1X6FtsNitQclqN2l9L5lXwi6JVEyfdkBsOLnI/ZQJ6G9Pmh4t7V9jeiytMICmXpoXvS1QpnnwzFIqQ6SFP5tIS7V8LC9l1569MDs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Nm5yyRv3; arc=none smtp.client-ip=95.215.58.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Nm5yyRv3" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1714178263; 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: in-reply-to:in-reply-to:references:references; bh=Gfv3iMSIWQC4QbQ/6GXaLS8Cjd7JxtChDyD5rQgDX9Q=; b=Nm5yyRv30txwaGJ50+RpR3dkkQIdU/cAkah0rz5E9NaWS6JEnqIlf8pCbX0XdNDBFnxc6N Hbz4uF6xZb+psVAA6G6MVW0R9CvKnIaxzNY6sPTfTQEuMd3bY+WiOBBBHx+n4a1jgGVc7m SpP+ZPeUku+xQYxxAw2TOWgKmw/JcxQ= From: Shakeel Butt To: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/7] memcg: reduce memory size of mem_cgroup_events_index Date: Fri, 26 Apr 2024 17:37:27 -0700 Message-ID: <20240427003733.3898961-2-shakeel.butt@linux.dev> In-Reply-To: <20240427003733.3898961-1-shakeel.butt@linux.dev> References: <20240427003733.3898961-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" mem_cgroup_events_index is a translation table to get the right index of the memcg relevant entry for the general vm_event_item. At the moment, it is defined as integer array. However on a typical system the max entry of vm_event_item (NR_VM_EVENT_ITEMS) is 113, so we don't need to use int as storage type of the array. For now just use int8_t as type and add a BUILD_BUG_ON() and will switch to short once NR_VM_EVENT_ITEMS touches 127. Signed-off-by: Shakeel Butt Reviewed-by: Roman Gushchin --- mm/memcontrol.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 602ad5faad4d..53769d06053f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -607,11 +607,14 @@ static const unsigned int memcg_vm_event_stat[] =3D { }; =20 #define NR_MEMCG_EVENTS ARRAY_SIZE(memcg_vm_event_stat) -static int mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly; +static int8_t mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly; =20 static void init_memcg_events(void) { - int i; + int8_t i; + + /* Switch to short once this failure occurs. */ + BUILD_BUG_ON(NR_VM_EVENT_ITEMS >=3D 127 /* INT8_MAX */); =20 for (i =3D 0; i < NR_MEMCG_EVENTS; ++i) mem_cgroup_events_index[memcg_vm_event_stat[i]] =3D i + 1; --=20 2.43.0