From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH v7 01/16] hashtable: introduce a small and naive hashtable Date: Mon, 29 Oct 2012 09:18:09 -0700 Message-ID: <20121029161809.GA4066@htj.dyndns.org> References: <1351450948-15618-1-git-send-email-levinsasha928@gmail.com> <20121029112907.GA9115@Krystal> <20121029161412.GB18944@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20121029161412.GB18944@Krystal> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dev-bounces-yBygre7rU0TnMu66kgdUjQ@public.gmane.org Errors-To: dev-bounces-yBygre7rU0TnMu66kgdUjQ@public.gmane.org To: Mathieu Desnoyers Cc: snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, neilb-l3A5Bk7waGM@public.gmane.org, fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Trond.Myklebust-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org, bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org, paul.gortmaker-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, aarcange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, rds-devel-N0ozoZBvEnrZJqsBc5GL+g@public.gmane.org, eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, venkat.x.venkatsubra-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, ccaulfie-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, mingo-X9Un+BFzKDI@public.gmane.org, dev-yBygre7rU0TnMu66kgdUjQ@public.gmane.org, ericvh-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org, rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org, teigland-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Sasha Levin , axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ejt-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org, lw-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org List-Id: dm-devel.ids Hello, On Mon, Oct 29, 2012 at 12:14:12PM -0400, Mathieu Desnoyers wrote: > Most of the calls to this initialization function apply it on zeroed > memory (static/kzalloc'd...), which makes it useless. I'd actually be in > favor of removing those redundant calls (as I pointed out in another > email), and document that zeroed memory don't need to be explicitly > initialized. > > Those sites that need to really reinitialize memory, or initialize it > (if located on the stack or in non-zeroed dynamically allocated memory) > could use a memset to 0, which will likely be faster than setting to > NULL on many architectures. I don't think it's a good idea to optimize out the basic encapsulation there. We're talking about re-zeroing some static memory areas which are pretty small. It's just not worth optimizing out at the cost of proper initializtion. e.g. We might add debug fields to list_head later. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-pb0-f46.google.com ([209.85.160.46]:39449 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759511Ab2J2QSP (ORCPT ); Mon, 29 Oct 2012 12:18:15 -0400 Date: Mon, 29 Oct 2012 09:18:09 -0700 From: Tejun Heo To: Mathieu Desnoyers Cc: Sasha Levin , torvalds@linux-foundation.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com, davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu, ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com, netdev@vger.kernel.org, josh@joshtriplett.org, eric.dumazet@gmail.com, axboe@kernel.dk, agk@redhat.com, dm-devel@redhat.com, neilb@suse.de, ccaulfie@redhat.com, teigland@redhat.com, Trond.Myklebust@netapp.com, bfields@fieldses.org, fweisbec@gmail.com, jesse@nicira.com, venkat.x.venkatsubra@oracle.com, ejt@redhat.com, snitzer@redhat.com, edumazet@google.com, linux-nfs@vger.kernel.org, dev@openvswitch.org, rds-devel@oss.oracle.com, lw@cn.fujitsu.com Subject: Re: [PATCH v7 01/16] hashtable: introduce a small and naive hashtable Message-ID: <20121029161809.GA4066@htj.dyndns.org> References: <1351450948-15618-1-git-send-email-levinsasha928@gmail.com> <20121029112907.GA9115@Krystal> <20121029161412.GB18944@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20121029161412.GB18944@Krystal> Sender: linux-nfs-owner@vger.kernel.org List-ID: Hello, On Mon, Oct 29, 2012 at 12:14:12PM -0400, Mathieu Desnoyers wrote: > Most of the calls to this initialization function apply it on zeroed > memory (static/kzalloc'd...), which makes it useless. I'd actually be in > favor of removing those redundant calls (as I pointed out in another > email), and document that zeroed memory don't need to be explicitly > initialized. > > Those sites that need to really reinitialize memory, or initialize it > (if located on the stack or in non-zeroed dynamically allocated memory) > could use a memset to 0, which will likely be faster than setting to > NULL on many architectures. I don't think it's a good idea to optimize out the basic encapsulation there. We're talking about re-zeroing some static memory areas which are pretty small. It's just not worth optimizing out at the cost of proper initializtion. e.g. We might add debug fields to list_head later. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx169.postini.com [74.125.245.169]) by kanga.kvack.org (Postfix) with SMTP id 522736B005A for ; Mon, 29 Oct 2012 12:18:15 -0400 (EDT) Received: by mail-pa0-f41.google.com with SMTP id fa10so3849566pad.14 for ; Mon, 29 Oct 2012 09:18:14 -0700 (PDT) Date: Mon, 29 Oct 2012 09:18:09 -0700 From: Tejun Heo Subject: Re: [PATCH v7 01/16] hashtable: introduce a small and naive hashtable Message-ID: <20121029161809.GA4066@htj.dyndns.org> References: <1351450948-15618-1-git-send-email-levinsasha928@gmail.com> <20121029112907.GA9115@Krystal> <20121029161412.GB18944@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121029161412.GB18944@Krystal> Sender: owner-linux-mm@kvack.org List-ID: To: Mathieu Desnoyers Cc: Sasha Levin , torvalds@linux-foundation.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com, davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu, ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com, netdev@vger.kernel.org, josh@joshtriplett.org, eric.dumazet@gmail.com, axboe@kernel.dk, agk@redhat.com, dm-devel@redhat.com, neilb@suse.de, ccaulfie@redhat.com, teigland@redhat.com, Trond.Myklebust@netapp.com, bfields@fieldses.org, fweisbec@gmail.com, jesse@nicira.com, venkat.x.venkatsubra@oracle.com, ejt@redhat.com, snitzer@redhat.com, edumazet@google.com, linux-nfs@vger.kernel.org, dev@openvswitch.org, rds-devel@oss.oracle.com, lw@cn.fujitsu.com Hello, On Mon, Oct 29, 2012 at 12:14:12PM -0400, Mathieu Desnoyers wrote: > Most of the calls to this initialization function apply it on zeroed > memory (static/kzalloc'd...), which makes it useless. I'd actually be in > favor of removing those redundant calls (as I pointed out in another > email), and document that zeroed memory don't need to be explicitly > initialized. > > Those sites that need to really reinitialize memory, or initialize it > (if located on the stack or in non-zeroed dynamically allocated memory) > could use a memset to 0, which will likely be faster than setting to > NULL on many architectures. I don't think it's a good idea to optimize out the basic encapsulation there. We're talking about re-zeroing some static memory areas which are pretty small. It's just not worth optimizing out at the cost of proper initializtion. e.g. We might add debug fields to list_head later. Thanks. -- tejun -- 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