From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jack Wang Subject: Re: [PATCH] IB/srp: add change_queue_depth and change_queue_type support Date: Tue, 27 Aug 2013 18:39:04 +0200 Message-ID: <521CD628.8090902@profitbricks.com> References: <521B5DD5.3020804@profitbricks.com> <521C63FA.3070709@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <521C63FA.3070709-HInyCGIudOg@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche Cc: Roland Dreier , David Dillow , Sebastian Riemer , linux-rdma List-Id: linux-rdma@vger.kernel.org snip > This code seems incorrect to me for the SRP protocol. In the SRP > protocol, although there is no TCQ support, queue depths above one are > supported. > > I also have a more general remark. There is no TCQ support in the SRP > protocol, which means that sdev->tagged_supported is always 0 (false). > So my recommendation is to leave out all code that depends on "if > (sdev->tagged_supported)" and to remove the "if > (!sdev->tagged_supported)" tests. > > Bart. Hello Bart, I look into scsi core about above statement: In drivers/scsi/scsi_scan.c:865: if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) && !(*bflags & BLIST_NOTQ)) sdev->tagged_supported = 1; It check inquiry result byte 7 with cmdque bit. inquiry result of a disk export through srp/srpt sg_inq /dev/sdb standard INQUIRY: PQual=0 Device_type=0 RMB=0 version=0x06 [SPC-4] [AERC=0] [TrmTsk=0] NormACA=0 HiSUP=0 Resp_data_format=2 SCCS=0 ACC=0 TPGS=0 3PC=0 Protect=0 [BQue=0] EncServ=0 MultiP=1 (VS=0) [MChngr=0] [ACKREQQ=0] Addr16=0 [RelAdr=0] WBus16=0 Sync=0 Linked=0 [TranDis=0] CmdQue=1 [SPI: Clocking=0x0 QAS=0 IUS=0] length=66 (0x42) Peripheral device type: disk Vendor identification: SCST_FIO Product identification: vol0 Product revision level: 300 Unit serial number: 609bbc13 So the sdev_>tagged_supported will be set in this case In srpr16 p38 The TASK ATTRIBUTE field is defined in table 21, it includes support for: head of queue ordered simple Do I miss something? Regards, Jack -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html