On Fri, 30 Jun 2023, NeilBrown wrote:
>
> I agree that an a priori cap on number of threads is not ideal.
> Have you considered using the xarray to only store busy threads?
> I think its lookup mechanism mostly relies on a bitmap of present
> entries, but I'm not completely sure.
It might be event better to use xa_set_mark() and xa_clear_mark() to
manage the busy state.
These are not atomic so you would need an atomic operation in the rqst.
#define XA_MARK_IDLE XA_MARK_1
do {
rqstp = xa_find(xa, ..., XA_MARK_IDLE);
if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) {
xa_clear_mark(xa, rqstp->xa_index, XA_MARK_IDLE);
break;
}
} while {rqstp);
xa_find() should be nearly as fast at find_next_bit()
NeilBrown
