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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 6 Feb 2019 13:34:34 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x16DYXml1769828 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 6 Feb 2019 13:34:33 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F001D4C04E; Wed, 6 Feb 2019 13:34:32 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D871D4C040; Wed, 6 Feb 2019 13:34:32 +0000 (GMT) Received: from t480-pf1aa2c2 (unknown [9.152.212.148]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Wed, 6 Feb 2019 13:34:32 +0000 (GMT) Received: from bblock by t480-pf1aa2c2 with local (Exim 4.91) (envelope-from ) id 1grNLU-0006JD-FE; Wed, 06 Feb 2019 14:34:32 +0100 Date: Wed, 6 Feb 2019 14:34:32 +0100 From: Benjamin Block To: John Garry Cc: Christoph Hellwig , Keith Busch , Hannes Reinecke , Thomas Gleixner , Marc Zyngier , "axboe@kernel.dk" , Peter Zijlstra , Michael Ellerman , Linuxarm , "linux-kernel@vger.kernel.org" , Hannes Reinecke , "linux-scsi@vger.kernel.org" , "linux-block@vger.kernel.org" Subject: Re: Question on handling managed IRQs when hotplugging CPUs References: <86d5028d-44ab-3696-f7fe-828d7655faa9@huawei.com> <745609be-b215-dd2d-c31f-0bd84572f49f@suse.de> <42d149c5-0380-c357-8811-81015159ac04@huawei.com> <20190205145244.GB28023@localhost.localdomain> <20190205182325.GA3302@lst.de> <3413b0b1-cb3f-3b09-106d-89cf8be30178@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3413b0b1-cb3f-3b09-106d-89cf8be30178@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 19020613-4275-0000-0000-0000030C2A7D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19020613-4276-0000-0000-0000381A2FF2 Message-Id: <20190206133432.GB14106@t480-pf1aa2c2> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-06_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=908 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902060107 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 06, 2019 at 09:21:40AM +0000, John Garry wrote: > On 05/02/2019 18:23, Christoph Hellwig wrote: > > On Tue, Feb 05, 2019 at 03:09:28PM +0000, John Garry wrote: > > > For SCSI devices, unfortunately not all IO sent to the HW originates from > > > blk-mq or any other single entity. > > > > Where else would SCSI I/O originate from? > > Please note that I was referring to other management IO, like SAS SMP, TMFs, > and other proprietary commands which the driver may generate for the HBA - > https://marc.info/?l=linux-scsi&m=154831889001973&w=2 discusses some of them > also. > Especially the TMFs send via SCSI EH are a bit of a pain I guess, because they are entirely managed by the device drivers, but depending on the device driver they might not even qualify for the problem Hannes is seeing. -- With Best Regards, Benjamin Block / Linux on IBM Z Kernel Development IBM Systems & Technology Group / IBM Deutschland Research & Development GmbH Vorsitz. 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