From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH v1 5/10] ext4: Add DX_HASH_SIPHASH24 support Date: Wed, 24 Sep 2014 11:35:31 -0400 Message-ID: <20140924153531.GK17784@thunk.org> References: <20140924014744.GJ17784@thunk.org> <20140924030828.18454.qmail@ns.horizon.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: adilger@dilger.ca, linux-ext4@vger.kernel.org To: George Spelvin Return-path: Received: from imap.thunk.org ([74.207.234.97]:46309 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753739AbaIXPff (ORCPT ); Wed, 24 Sep 2014 11:35:35 -0400 Content-Disposition: inline In-Reply-To: <20140924030828.18454.qmail@ns.horizon.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Sep 23, 2014 at 11:08:28PM -0400, George Spelvin wrote: > > Still, it would probably simpler to not try to assign > > DX_HASH_SIPHASH24 to be 6, and to leave better comments about how the > > hash values are used. > > Is that "not try" supposed to be in there? Sorry, typo. Yes, it would be better to assign DX_HASH_SIPHASH24 to be 6, and not to assign the code points 3, 4, and 5 just to be safe. > BTW, initial benchmarking isn't showing much. I created a 4 GB file > syste, on a RAM disk with -i 1024, and tried the following: > DEV=/tmp/FS > MNT=/mnt (I assume you're using tmpfs.) There would be less overhead if you actually used a real ramdisk, i.e., /dev/ram0, which might reduce some of the variance and increase the percentage of the difference, but yeah, it's not that surprising that we're not seeing much difference. - Ted