hg.3 (2010 09)

hg(3) hg(3)

(Mercury Library)

critical region

release lock

hg_setcrit(CRIT_OFF, WILLING_TO_BLOCK);

Or ...

hg_setcrit(lock_address , WILLING_TO_BLOCK);

acquire lock

critical region

release lock

hg_setcrit(CRIT_OFF, WILLING_TO_BLOCK);

It is never absolutely necessary to set WILLING_TO_BLOCK

, but it reduces your chances of being

switched out during the critical region. Remember that

WILLING_TO_BLOCK means that you are wil-

ling to block during the

hg_setcrit() call, not during the critical region.

Note

All information returned by the initiative should be considered hints. By their very nature, and the

nature of scheduling user processes and threads, much of this information can theoretically be stale

immediately after its delivery to the user, or at any time after that. User code must take this into account

in its design.

The

libpthread library links with the Mercury Library in order to decide on the scheduling of threads

at any point of time. Hence, applications which are using both, libpthread and libhg need to take

care that libpthread is already using libhg for scheduling decisions. The applications may still how-

ever use the Mercury APIs if they feel the need to do so.

WARNINGS

Remember that this thread information may be stale any time after the kernel post it. Be careful how

you rely on it. It is totally up to the user code to take care of this while writing code.

AUTHOR

The Mercury APIs were developed by Hewlett-Packard Company.