From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gordan Bobic Subject: Re: Offline Deduplication for Btrfs Date: Wed, 05 Jan 2011 20:25:41 +0000 Message-ID: <4D24D3C5.6080803@bobich.net> References: <1294245410-4739-1-git-send-email-josef@redhat.com> <4D24AD92.4070107@bobich.net> <201101051941.13268.diegocg@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed To: BTRFS MAILING LIST Return-path: In-Reply-To: <201101051941.13268.diegocg@gmail.com> List-ID: On 01/05/2011 06:41 PM, Diego Calleja wrote: > On Mi=E9rcoles, 5 de Enero de 2011 18:42:42 Gordan Bobic escribi=F3: >> So by doing the hash indexing offline, the total amount of disk I/O >> required effectively doubles, and the amount of CPU spent on doing t= he >> hashing is in no way reduced. > > But there are people who might want to avoid temporally the extra cos= t > of online dedup, and do it offline when the server load is smaller. The point is that the offline dedup is actually twice as expensive, and= =20 the hashing part is nowhere nearly expensive as disk I/O. Disk I/O is=20 very limited today, compared to CPU time. Gordan -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html