CODEWITHSUNDEEP
multithreadingunixsolarissolaris-10
CCNA
CCNA

Reputation: 387

Is there a way to find out which core each thread of an app is binding to?

Say, a multi-threading app runs on a 8-core Solaris. Is there a way to list the mapping between each thread and core #?

Thanks,

Upvotes: 0

Views: 365

Answers (1)

jim mcnamara
jim mcnamara

Reputation: 16389

First off, you can write C code to inquire after each thread in a process Open /proc/[id]/lwp/[tid]/lwpsinfo there and fetch it into a lwpsinfo_t struct defined in procfs.h

processorid_t pr_onpro;         /* processor which last ran this lwp */
processorid_t pr_bindpro;       /* processor to which lwp is bound */

Are the two members of interest to you. Before you waste your time

Next before you waste a lot of time (assuming zones):

prctl -i zone {ZONENAME} run by root in the global zone only. You get output like this:

NAME    PRIVILEGE       VALUE    FLAG   ACTION                       RECIPIENT
zone.max-swap
        system          16.0EB    max   deny                                 -
zone.max-locked-memory
        system          16.0EB    max   deny                                 -
zone.max-shm-memory
        system          16.0EB    max   deny                                 -
zone.max-shm-ids
        system          16.8M     max   deny                                 -
zone.max-sem-ids
        system          16.8M     max   deny                                 -
zone.max-msg-ids
        system          16.8M     max   deny                                 -
zone.max-lwps
        system          2.15G     max   deny                                 -
zone.cpu-cap
        privileged      1.20K       -   deny                                 -
        system          4.29G     inf   deny                                 -
zone.cpu-shares
        privileged          1       -   none                                 -
        system          65.5K     max   none                                 -

zone.cpu-cap 1.20K means 1200 == means percent. So 1200 means 12 cpus. If I were your admin there is no way a DEV or TEST zone would have 64 cores. So check it first.

Plus, it seems your assumptions are wrong. Unless affinity (processor sets, etc.) is enabled the system assigns cpus to threads using the currently enabled scheduling algorithm (FSS, etc.) This means any thread can go to any available cpu at any time depending on the scheduler and load.

Upvotes: 1

Related Questions