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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: eaec5169-17bf-4180-7d05-08d7825e6fb8 X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Dec 2019 19:30:41.2091 (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: zHgUyAZSfN44ZnCLBOHgaydioPyFeOIYx3umxCDnIYhqx6DsdlCmUm66uTiyDSo5 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR15MB3712 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-16_07:2019-12-16,2019-12-16 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 suspectscore=0 phishscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1011 bulkscore=0 spamscore=0 mlxlogscore=581 mlxscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912160164 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Dec 14, 2019 at 02:25:14PM -0500, Neal Cardwell wrote: > On Fri, Dec 13, 2019 at 9:00 PM Eric Dumazet wro= te: > > > > > > > > On 12/13/19 4:47 PM, Martin KaFai Lau wrote: > > > This patch adds a helper to handle jiffies. Some of the > > > tcp_sock's timing is stored in jiffies. Although things > > > could be deduced by CONFIG_HZ, having an easy way to get > > > jiffies will make the later bpf-tcp-cc implementation easier. > > > > > > > ... > > > > > + > > > +BPF_CALL_2(bpf_jiffies, u64, in, u64, flags) > > > +{ > > > + if (!flags) > > > + return get_jiffies_64(); > > > + > > > + if (flags & BPF_F_NS_TO_JIFFIES) { > > > + return nsecs_to_jiffies(in); > > > + } else if (flags & BPF_F_JIFFIES_TO_NS) { > > > + if (!in) > > > + in =3D get_jiffies_64(); > > > + return jiffies_to_nsecs(in); > > > + } > > > + > > > + return 0; > > > +} > > > > This looks a bit convoluted :) > > > > Note that we could possibly change net/ipv4/tcp_cubic.c to no longer us= e jiffies at all. > > > > We have in tp->tcp_mstamp an accurate timestamp (in usec) that can be c= onverted to ms. >=20 > If the jiffies functionality stays, how about 3 simple functions that > correspond to the underlying C functions, perhaps something like: >=20 > bpf_nsecs_to_jiffies(nsecs) > bpf_jiffies_to_nsecs(jiffies) > bpf_get_jiffies_64() >=20 > Separate functions might be easier to read/maintain (and may even be > faster, given the corresponding reduction in branches). Yes. It could be different bpf helpers. I will take another look on these. I may not need the nsecs <=3D> jiffies with CONFIG_HZ and Andrii's recent extern var support. The first attempt I tried end-up a lot of codes on the bpf_prog side. I may not have done it right. I will give it another try on this side. Thanks for the feedbacks!