From owner-freebsd-scsi@FreeBSD.ORG Fri Jun 1 06:13:03 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 3CC8A16A400 for ; Fri, 1 Jun 2007 06:13:03 +0000 (UTC) (envelope-from lydianconcepts@gmail.com) Received: from nz-out-0506.google.com (nz-out-0506.google.com [64.233.162.227]) by mx1.freebsd.org (Postfix) with ESMTP id DD73D13C468 for ; Fri, 1 Jun 2007 06:13:02 +0000 (UTC) (envelope-from lydianconcepts@gmail.com) Received: by nz-out-0506.google.com with SMTP id 14so364250nzn for ; Thu, 31 May 2007 23:13:02 -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=Nq5vAzoTS67C6goaKansjJpt4afy2ztZnIt3j4UunPoWVD61/bJTx8L5+IfdaC0sPMabAvw/NHsSRffoiGfyA6pWtf/XFovFCVY8cJe1JuMdGaBsDdZdKBjnIW7T/zOvM8uxbp6FLY7pSEW5AAngSoFzn7y19RM/jWLhE/8g/6o= 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=d479HOdGQA0Uwvm7X9fHr5OyxiEmDUvkdQGh1VGqSLtNJqyfvhaN6XKrq5YscqwxqJYNdvMlAcz1nnPmWAV5qUPwbZLTWQzEiZz4K9SK6BpZAevwj7QX7IZJPm43VwEIji6Ykta8flbk7BqyBcas+44g6eAtj3YOh+qx027d9c4= Received: by 10.114.89.1 with SMTP id m1mr1449993wab.1180678381818; Thu, 31 May 2007 23:13:01 -0700 (PDT) Received: by 10.114.24.2 with HTTP; Thu, 31 May 2007 23:13:01 -0700 (PDT) Message-ID: <7579f7fb0705312313p5c766887s1c2e598884513d6e@mail.gmail.com> Date: Thu, 31 May 2007 23:13:01 -0700 From: "Matthew Jacob" To: "Hidetoshi Shimokawa" In-Reply-To: <626eb4530705312300n177e677cyac2e8ba69039160d@mail.gmail.com> 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> <7579f7fb0705312147p60255cf2r9eac5d5eb8aa5236@mail.gmail.com> <626eb4530705312300n177e677cyac2e8ba69039160d@mail.gmail.com> 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 06:13:03 -0000 Yes. None of the extant stuff is deployable as solid solution without reworking. On 5/31/07, Hidetoshi Shimokawa wrote: > Yes, scsi_target(8) is an example. > But the problem I described is actually a problem of targ(4) (scsi_target.c). > The userland can do nothing about this problem. > Or do you mean targ(4) is also an example? > > On 6/1/07, Matthew Jacob wrote: > > 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" > > > > > > > > > > -- > /\ Hidetoshi Shimokawa > \/ simokawa@FreeBSD.ORG >