From owner-freebsd-scsi@FreeBSD.ORG Fri Jun 1 04:47:08 2007 Return-Path: X-Original-To: freebsd-scsi@freebsd.org Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 8B0D716A421 for ; Fri, 1 Jun 2007 04:47:08 +0000 (UTC) (envelope-from lydianconcepts@gmail.com) Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.176]) by mx1.freebsd.org (Postfix) with ESMTP id 660C713C447 for ; Fri, 1 Jun 2007 04:47:08 +0000 (UTC) (envelope-from lydianconcepts@gmail.com) Received: by wa-out-1112.google.com with SMTP id m33so523433wag for ; Thu, 31 May 2007 21:47:08 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=MhH8W/cmKSeAv1svWITf9JLHaX18yZGRmgmK2DSaPj3EUASx/2l00i6Lei94flr7nRUPDfiwUdx2YmluV572D7OLrIW/lBHW2i501i1K1flOhQpS5vwGtQ8lmnuq0KGaltValRxuxglqzmTlQRJEEAQ5K4HyJ87yjugqRsRkBW0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=K7tFcVbxrY7/bq3TExkfKIvixY9czBNYGLerlAD0nCOPdRmlOcrLK/PFNm5r/0lXHEDaxYiCRH+VdymhlkejpVqwGNNYC61H9ScsAzA6uSH+A1Cb7BZYlfQjBKlS6WqiqriA5ufvnFupHgpk+uGvyQBaUg0uPCzKAyk8dsnrB8w= Received: by 10.114.209.1 with SMTP id h1mr1435140wag.1180673228096; Thu, 31 May 2007 21:47:08 -0700 (PDT) Received: by 10.114.24.2 with HTTP; Thu, 31 May 2007 21:47:08 -0700 (PDT) Message-ID: <7579f7fb0705312147p60255cf2r9eac5d5eb8aa5236@mail.gmail.com> Date: Thu, 31 May 2007 21:47:08 -0700 From: "Matthew Jacob" To: "Hidetoshi Shimokawa" In-Reply-To: <465F955E.7050103@samsco.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <86tztspdil.wl%simokawa@FreeBSD.ORG> <465F955E.7050103@samsco.org> Cc: freebsd-scsi@freebsd.org Subject: Re: scsi_target with multiple luns X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Jun 2007 04:47:08 -0000 Remember that scsi_target is an example. A fine example, but an example. Having a single user process that can be shot and killed, no matter how multithreaded or AIO'd, is not necessarily the wisest choice for building a target device. On 5/31/07, Scott Long wrote: > Hidetoshi Shimokawa wrote: > > I have not fully analyzed the problem but I'll describe it just for a note. > > I'd like to ask maintainers of scsi_target for further analysis. > > > > I experiance a problem with small number(1) of simq and multiple > > scsi_target(8) instances. > > > > As far as I understand, the following situation could occur under a fairly > > heavy load. > > > > 1. process A send a request -> cam send to sim > > 2. process B send a request -> blocked because the simq is full > > 3. the request of process A is finished (in the context of process A) > > 4. cam/scsi_target tries to send the request of process B. > > But the mapped memory is of process A, and scsi_target send wrong > > ccb to sim. > > > > Maybe, we should rewrite scsi_target in kernel space with GEOM support.. > > I'm unclear on how GEOM would fix this. Also, scsi targets aren't > always DA devices. I dedicated scsi_da_target device that is backed > by GEOM might be interesting, though. Even more interesting would be > a direct DMA method that required no KVA mappings for the data. > > Scott > > _______________________________________________ > freebsd-scsi@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-scsi > To unsubscribe, send any mail to "freebsd-scsi-unsubscribe@freebsd.org" >