[Cbe-oss-dev] spu sched problems

Ishizaki Kou kou.ishizaki at toshiba.co.jp
Tue Mar 6 23:57:30 EST 2007


We met two problems about spu scheduler when we tested
atomic_op_sample in CellSDK 2.0.

We tested on a hardware that has only 7 spus. These problems occur
when number of spu threads is greater than number of physical spus.

Case #1 BUG: soft lockup detected

When spu_run syscall is executed and spu scheduler cannot find idle
spu, the calling thread falls in busy loop in spu_activate() and
it causes 'BUG: soft lockup detected'.

Case #2 spu yielding

If a spu thread is in a run queue, yielding spu occurs when any
running spu thread exits. But, if a spu thread exits before next spu
thread is queued, yielding spu doesn't occur and the next spu thread
will not be scheduled.

Beat regards,
Kou Ishizaki

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