From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx182.postini.com [74.125.245.182]) by kanga.kvack.org (Postfix) with SMTP id A7EC56B0044 for ; Thu, 2 Aug 2012 13:48:43 -0400 (EDT) Received: by bkcjc3 with SMTP id jc3so5309575bkc.14 for ; Thu, 02 Aug 2012 10:48:41 -0700 (PDT) Subject: Re: [RFC 1/4] hashtable: introduce a small and naive hashtable From: Eric Dumazet In-Reply-To: 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> <87txwl1dsq.fsf@xmission.com> <501AAC26.6030703@gmail.com> <87fw851c3d.fsf@xmission.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 02 Aug 2012 19:48:37 +0200 Message-ID: <1343929717.9299.358.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: "Eric W. Biederman" , Sasha Levin , Josh Triplett , Tejun Heo , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com On Thu, 2012-08-02 at 10:32 -0700, Linus Torvalds wrote: > On Thu, Aug 2, 2012 at 9:40 AM, Eric W. Biederman wrote: > > > > For a trivial hash table I don't know if the abstraction is worth it. > > For a hash table that starts off small and grows as big as you need it > > the incent to use a hash table abstraction seems a lot stronger. > > I'm not sure growing hash tables are worth it. > > In the dcache layer, we have an allocated-at-boot-time sizing thing, > and I have been playing around with a patch that makes the hash table > statically sized (and pretty small). And it actually speeds things up! By the way, anybody tried to tweak vmalloc() (or alloc_large_system_hash()) to use HugePages for those large hash tables ? -- 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