> From: Bruce Richardson [mailto:bruce.richard...@intel.com] > Sent: Tuesday, 13 May 2025 18.17 > > The "--lcores" EAL parameter has a very powerful syntax that can be > used > to provide precise control over lcore mappings. The docs however, only > provided a minimal description of what it can do. Augment the docs by > providing some examples of use of the option, and what the resulting > core mappings would be. > > Signed-off-by: Bruce Richardson <bruce.richard...@intel.com> > Acked-by: Morten Brørup <m...@smartsharesystems.com> > --- > doc/guides/linux_gsg/eal_args.include.rst | 27 +++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/doc/guides/linux_gsg/eal_args.include.rst > b/doc/guides/linux_gsg/eal_args.include.rst > index 01fe6a3006..d530215784 100644 > --- a/doc/guides/linux_gsg/eal_args.include.rst > +++ b/doc/guides/linux_gsg/eal_args.include.rst > @@ -23,6 +23,33 @@ Lcore-related options > The grouping ``()`` can be omitted for single element group. > The ``@`` can be omitted if cpus and lcores have the same value. > > + Examples: > + > + ``--lcores=1-3``: Run threads on physical CPUs 1, 2 and 3, > + with each thread having the same lcore id as the physical CPU id. > + > + ``--lcores=1@(1,2)``: Run a single thread with lcore id 1, > + but with that thread bound to both physical CPUs 1 and 2, > + so it can run on either, as determined by the operating system. > + > + ``--lcores='1@31,2@32,3@33'``: Run threads having internal lcore > ids of 1, 2 and 3, > + but with the threads being bound to physical CPUs 31, 32 and 33 > respectively. > + > + ``--lcores='(1-3)@(31-33)'``: Run three threads with lcore ids 1, > 2 and 3. > + Unlike the previous example above, > + each of these threads is not bound to one specific physical CPU, > + but rather, all three threads are instead bound to the three > physical CPUs 31, 32 and 33. > + This means that each of the three threads can move between the > physical CPUs 31-33, > + as decided by the OS as the application runs. > + > + ``--lcores=(1-3)@20``: Run three threads, with lcore ids 1, 2 and > 3, > + where all three threads are bound to (can only run on) physical > CPU 20.
Just noticed... Some examples use: --lcores=XYZ And some use: --lcores='XYZ' Are the apostrophes required in some cases? If not, please remove them. > + > +.. Note:: > + Binding multiple DPDK lcores to a single physical CPU can cause > problems with poor performance > + or deadlock when using DPDK rings or memory pools or spinlocks. > + Such a configuration should only be used with care. > + > .. Note:: > At a given instance only one core option ``--lcores``, ``-l`` or > ``-c`` can > be used. > -- > 2.45.2
