From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: stgt a new version of iscsi target? Date: Wed, 14 Dec 2005 13:55:53 -0600 Message-ID: <43A078C9.1040007@cs.wisc.edu> References: <43972C2D.9060500@cs.wisc.edu> <43987F75.2000301@vlnb.net> <1134071268.3259.29.camel@mulgrave> <4399A2D7.2040402@vlnb.net> <1134143298.3598.21.camel@mulgrave> <439AF52B.7060203@vlnb.net> <439B1965.90603@cs.wisc.edu> <43A03500.1040500@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <43A03500.1040500@vlnb.net> Sender: iscsitarget-devel-admin@lists.sourceforge.net Errors-To: iscsitarget-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Vladislav Bolkhovitin Cc: James Bottomley , johan@capvert.se, iscsitarget-devel@lists.sourceforge.net, mingz@ele.uri.edu, stgt , Robert Whitehead , scst-devel@lists.sourceforge.net, linux-scsi@vger.kernel.org, Christoph Hellwig List-Id: linux-scsi@vger.kernel.org Vladislav Bolkhovitin wrote: > Mike Christie wrote: > >>> >>> Are you sure that there are no now or will be available in the >>> nearest feature such (eg iSCSI) SCSI arrays with response >>> time/latency so small that having 5 (five) context switches or more >>> per command, some of which include map/unmap operations, will not >>> increase the latency too much? I mean, eg NFS server, which >>> originally was user space daemon and many people didn't want it in >>> the kernel. Eventually, it's in. I don't see any fundamental >>> difference between NFS server and SCSI target server, >> >> >> >> Isn't the reason a NFS server is still in the kernel is becuase some >> of the locking difficulties? > > > Might be. But from what I remember, the major reason was the > performance. After googling a bit I found many acknowledgments of that. > I do not think we are going to get anywhere with this type of thread :( We should try to compare at least one of the userspace *nbd implementations with the unh target in scst. I see some that just do some basic socket ops (no sendfile type hook in even) for the network part then just async or normal read/writes. I do not want to comapre FC to nbd, but maybe comparing software iscsi to userspace nbd is a little more fair. I think ata over ethernet has a userspace target too. Is the unh target defaults set ok for performance testing, or could you send some off list, so we can at least test those. ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click