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charset="us-ascii" Content-ID: <315663F0F9B1B74796DD7C74E49CFAEE@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 3e36b6d6-12df-4fb1-8438-08d7641670ea X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Nov 2019 06:39:44.1150 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: SmZON9wcauonpYT9ROq5ZX6r8UB1P6E91U0VJUVYb3zfO+rdV0GN8OPIpMSUPl04Q4T4zewyLNM4Pw0Rfimo6Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1950 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-08_01:2019-11-07,2019-11-08 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 impostorscore=0 clxscore=1015 mlxscore=0 suspectscore=0 bulkscore=0 phishscore=0 adultscore=0 mlxlogscore=862 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911080063 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org > On Nov 7, 2019, at 8:20 PM, Andrii Nakryiko wrote: >=20 > Add ability to memory-map contents of BPF array map. This is extremely us= eful > for working with BPF global data from userspace programs. It allows to av= oid > typical bpf_map_{lookup,update}_elem operations, improving both performan= ce > and usability. >=20 > There had to be special considerations for map freezing, to avoid having > writable memory view into a frozen map. To solve this issue, map freezing= and > mmap-ing is happening under mutex now: > - if map is already frozen, no writable mapping is allowed; > - if map has writable memory mappings active (accounted in map->writecnt= ), > map freezing will keep failing with -EBUSY; > - once number of writable memory mappings drops to zero, map freezing ca= n be > performed again. >=20 > Only non-per-CPU arrays are supported right now. Maps with spinlocks can'= t be > memory mapped either. >=20 > Cc: Rik van Riel > Cc: Johannes Weiner > Signed-off-by: Andrii Nakryiko Acked-by: Song Liu With one nit below.=20 [...] > - if (percpu) > + data_size =3D 0; > + if (percpu) { > array_size +=3D (u64) max_entries * sizeof(void *); > - else > - array_size +=3D (u64) max_entries * elem_size; > + } else { > + if (attr->map_flags & BPF_F_MMAPABLE) { > + data_size =3D (u64) max_entries * elem_size; > + data_size =3D round_up(data_size, PAGE_SIZE); > + } else { > + array_size +=3D (u64) max_entries * elem_size; > + } > + } >=20 > /* make sure there is no u32 overflow later in round_up() */ > - cost =3D array_size; > + cost =3D array_size + data_size; This is a little confusing. Maybe we can do=20 data_size =3D (u64) max_entries * (per_cpu ? sizeof(void *) : elem_size; if (attr->map_flags & BPF_F_MMAPABLE) data_size =3D round_up(data_size, PAGE_SIZE); =09 cost =3D array_size + data_size; So we use data_size in all cases.=20 Maybe also rename array_size. > if (percpu) > cost +=3D (u64)attr->max_entries * elem_size * num_possible_cpus(); And maybe we can also include this in data_size.=20 [...]