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Thu, 19 Jan 2023 16:04:08 GMT Received: from smtprelay04.fra02v.mail.ibm.com ([9.218.2.228]) by ppma03ams.nl.ibm.com (PPS) with ESMTPS id 3n3m16pw8c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 19 Jan 2023 16:04:08 +0000 Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 30JG44qD25428620 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Jan 2023 16:04:04 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ABD362004B; Thu, 19 Jan 2023 16:04:04 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6B9AE20043; Thu, 19 Jan 2023 16:04:03 +0000 (GMT) Received: from [9.171.48.94] (unknown [9.171.48.94]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 19 Jan 2023 16:04:03 +0000 (GMT) Message-ID: <0ce7d96b8447a293b147976e5993cb053feb9c52.camel@linux.ibm.com> Subject: Re: [PATCH v4 4/7] s390/pci: Use dma-iommu layer From: Niklas Schnelle To: Matthew Rosato , Joerg Roedel , Will Deacon , Robin Murphy , Jason Gunthorpe , Wenjia Zhang Cc: Gerd Bayer , Pierre Morel , iommu@lists.linux.dev, linux-s390@vger.kernel.org, borntraeger@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, linux-kernel@vger.kernel.org, Julian Ruess Date: Thu, 19 Jan 2023 17:04:03 +0100 In-Reply-To: <50c22529-e0f4-9124-fdc0-c8da49300b18@linux.ibm.com> References: <20230104120543.308933-1-schnelle@linux.ibm.com> <20230104120543.308933-5-schnelle@linux.ibm.com> <71b9e85d-960f-7403-0113-135746127f3b@linux.ibm.com> <50c22529-e0f4-9124-fdc0-c8da49300b18@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.46.3 (3.46.3-1.fc37) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: mBCQhlILT8uXKEsgqOidgLiNpHkowUih X-Proofpoint-GUID: mBCQhlILT8uXKEsgqOidgLiNpHkowUih X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.122.1 definitions=2023-01-19_09,2023-01-19_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 bulkscore=0 mlxlogscore=709 clxscore=1015 suspectscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 priorityscore=1501 phishscore=0 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2301190125 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Thu, 2023-01-19 at 10:59 -0500, Matthew Rosato wrote: > On 1/19/23 6:03 AM, Niklas Schnelle wrote: > > > > > > > > > > > > > > > > > > =C2=A0 > > > > > > > > > > > > > > > > > >=20 > > > > > > > > > > > > > > > > > > =C2=A0static char *pci_sw_names[] =3D { > > > > > > > > > > > > > > > > > > - "Allocated pages", > > > > > > > > > > > > > > > > > > +/* TODO "Allocated pages", */ > > > > > > > > > >=20 > > > > > > > > > > ? Forgot to finish this? > >=20 > > Definitely forgot to remove the TODO. I think my latest plan was to > > just remove this counter. With the DMA API conversion the > > dma_map_ops.alloc and dma_map_ops.free move to common code and I don't > > see how we could differentiate these from map/unmap on our side. I'm > > not sure how helpful this counter really is either. If you're > > interested in how many pages are mapped long term I think it makes more > > sense to look at the difference between mapped and unmapped pages. What > > do you think? > > > > > > > > >=20 >=20 > Sounds reasonable to me, but I also note that without this series, when v= iewing statistics for a device, mapped - unmapped !=3D allocated. Maybe al= located pages was already broken, or is it taking into account something el= se that mapped - unmapped would not (maybe mapping the same page multiple t= imes)? >=20 >=20 Allocated Pages only counts the memory allocated via dma_map_ops.alloc so it would not count long term mappings of memory the driver allocated differently and then mapped for long term use.