From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx205.postini.com [74.125.245.205]) by kanga.kvack.org (Postfix) with SMTP id C5CCB6B004D for ; Thu, 2 Aug 2012 09:03:52 -0400 (EDT) Received: by bkcjc3 with SMTP id jc3so5149404bkc.14 for ; Thu, 02 Aug 2012 06:03:51 -0700 (PDT) Message-ID: <501A7AD3.7000008@gmail.com> Date: Thu, 02 Aug 2012 15:04:19 +0200 From: Sasha Levin MIME-Version: 1.0 Subject: Re: [RFC 1/4] hashtable: introduce a small and naive hashtable References: <20120731182330.GD21292@google.com> <50197348.9010101@gmail.com> <20120801182112.GC15477@google.com> <50197460.8010906@gmail.com> <20120801182749.GD15477@google.com> <50197E4A.7020408@gmail.com> <20120801202432.GE15477@google.com> <5019B0B4.1090102@gmail.com> <20120801224556.GF15477@google.com> <501A4FC1.8040907@gmail.com> <20120802103244.GA23318@leaf> <501A633B.3010509@gmail.com> In-Reply-To: <501A633B.3010509@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Josh Triplett Cc: Tejun Heo , torvalds@linux-foundation.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com On 08/02/2012 01:23 PM, Sasha Levin wrote: >> #define DEFINE_HASH_TABLE(name, length) struct hash_table name = { .count = length, .buckets = { [0 ... (length - 1)] = HLIST_HEAD_INIT } } > The limitation of this approach is that the struct hash_table variable must be 'static', which is a bit limiting - see for example the use of hashtable in 'struct user_namespace'. > What if we just use two possible decelerations? One of static structs and one for regular ones. struct hash_table { size_t bits; struct hlist_head buckets[]; }; #define DEFINE_HASHTABLE(name, bits) \ union { \ struct hash_table name; \ struct { \ size_t bits; \ struct hlist_head buckets[1 << bits]; \ } __name; \ } #define DEFINE_STATIC_HASHTABLE(name, bit) \ static struct hash_table name = { .bits = bit, \ .buckets = { [0 ... (bit - 1)] = HLIST_HEAD_INIT } } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org