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Tue, 24 Mar 2020 16:12:32 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02OGBonB079385; Tue, 24 Mar 2020 16:12:32 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 2yxw92wr2t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 24 Mar 2020 16:12:31 +0000 Received: from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 02OGCPoj014077; Tue, 24 Mar 2020 16:12:25 GMT Received: from [10.175.222.8] (/10.175.222.8) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 24 Mar 2020 09:12:24 -0700 Subject: Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support To: Dan Williams Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com, hch@lst.de, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org References: <158500767138.2088294.17131646259803932461.stgit@dwillia2-desk3.amr.corp.intel.com> <158500773552.2088294.8756587190550753100.stgit@dwillia2-desk3.amr.corp.intel.com> From: Joao Martins Message-ID: <9a6ff83f-095c-0689-d6d1-693a6e9c07e6@oracle.com> Date: Tue, 24 Mar 2020 16:12:21 +0000 MIME-Version: 1.0 In-Reply-To: <158500773552.2088294.8756587190550753100.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9570 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 spamscore=0 bulkscore=0 adultscore=0 mlxscore=0 malwarescore=0 mlxlogscore=999 suspectscore=5 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003240087 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9570 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 bulkscore=0 clxscore=1011 impostorscore=0 phishscore=0 suspectscore=5 mlxlogscore=999 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003240086 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/23/20 11:55 PM, Dan Williams wrote: > static ssize_t dev_dax_resize(struct dax_region *dax_region, > struct dev_dax *dev_dax, resource_size_t size) > { > resource_size_t avail = dax_region_avail_size(dax_region), to_alloc; > - resource_size_t dev_size = range_len(&dev_dax->range); > + resource_size_t dev_size = dev_dax_size(dev_dax); > struct resource *region_res = &dax_region->res; > struct device *dev = &dev_dax->dev; > - const char *name = dev_name(dev); > struct resource *res, *first; > + resource_size_t alloc = 0; > + int rc; > > if (dev->driver) > return -EBUSY; > @@ -684,38 +766,47 @@ static ssize_t dev_dax_resize(struct dax_region *dax_region, > * allocating a new resource. > */ > first = region_res->child; > - if (!first) > - return __alloc_dev_dax_range(dev_dax, dax_region->res.start, > - to_alloc); You probably want to retain the condition above? Otherwise it removes the ability to create new devices or resizing it , once we have zero-ed the last one. > - for (res = first; to_alloc && res; res = res->sibling) { > +retry: > + rc = -ENOSPC; > + for (res = first; res; res = res->sibling) { > struct resource *next = res->sibling; > - resource_size_t free; > > /* space at the beginning of the region */ > - free = 0; > - if (res == first && res->start > dax_region->res.start) > - free = res->start - dax_region->res.start; > - if (free >= to_alloc && dev_size == 0) > - return __alloc_dev_dax_range(dev_dax, > - dax_region->res.start, to_alloc); > - > - free = 0; > + if (res == first && res->start > dax_region->res.start) { > + alloc = min(res->start - dax_region->res.start, > + to_alloc); > + rc = __alloc_dev_dax_range(dev_dax, > + dax_region->res.start, alloc); > + break; > + } > + > + alloc = 0; > /* space between allocations */ > if (next && next->start > res->end + 1) > - free = next->start - res->end + 1; > + alloc = min(next->start - (res->end + 1), to_alloc); > > /* space at the end of the region */ > - if (free < to_alloc && !next && res->end < region_res->end) > - free = region_res->end - res->end; > - > - if (free >= to_alloc && strcmp(name, res->name) == 0) > - return __adjust_dev_dax_range(dev_dax, res, > - resource_size(res) + to_alloc); > - else if (free >= to_alloc && dev_size == 0) > - return __alloc_dev_dax_range(dev_dax, res->end + 1, > - to_alloc); > + if (!alloc && !next && res->end < region_res->end) > + alloc = min(region_res->end - res->end, to_alloc); > + > + if (!alloc) > + continue; > + > + if (adjust_ok(dev_dax, res)) { > + rc = __adjust_dev_dax_range(dev_dax, res, > + resource_size(res) + alloc); > + break; > + } > + rc = __alloc_dev_dax_range(dev_dax, res->end + 1, > + alloc); I am wondering if we should switch to: if (adjust_ok(...)) rc = __adjust_dev_dax_range(...); else rc = __alloc_dev_dax_range(...); And then a debug print at the end depicting whether and how did we grabbed space? Something like: dev_dbg(&dev_dax->dev, "%s(%d) %d", action, location, rc); Assuming we set @location to its values when we allocate space at the end, beginning or middle; and @action to whether we adjusted up/down or allocated new range. Essentially, something similar to namespaces scan_allocate() just to help troubleshoot? Regards, Joao