From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: Integration of SCST in the mainstream Linux kernel Date: Tue, 5 Feb 2008 10:18:11 -0800 (PST) Message-ID: References: <1201639331.3069.58.camel@localhost.localdomain> <47A05CBD.5050803@vlnb.net> <47A7049A.9000105@vlnb.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:50274 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755389AbYBESTA (ORCPT ); Tue, 5 Feb 2008 13:19:00 -0500 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Bart Van Assche Cc: James Bottomley , FUJITA Tomonori , Vladislav Bolkhovitin , Vu Pham , Andrew Morton , linux-scsi@vger.kernel.org, scst-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, "Nicholas A. Bellinger" On Tue, 5 Feb 2008, Bart Van Assche wrote: > > Results that I did not expect: > * A block transfer size of 1 MB is not enough to measure the maximal > throughput. The maximal throughput is only reached at much higher > block sizes (about 10 MB for SCST + SRP and about 100 MB for STGT + > iSER). Block transfer sizes over about 64kB are totally irrelevant for 99% of all people. Don't even bother testing anything more. Yes, bigger transfers happen, but a lot of common loads have *smaller* transfers than 64kB. So benchmarks that try to find "theoretical throughput" by just making big transfers should just be banned. They give numbers, yes, but the numbers are pointless. Linus