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Re: [Xen-devel] credit scheduler svc->flags access race?

Hi, Keir and George, thanks for your concerns.

Access race to svc->flags seems inevitably when csched_acct calls
    vm excutes PAUSE instruction.
    hypercalls call csched_vcpu_yield.

I had think about taking csched_private->lock in csched_vcpu_yield, but
csched_acct takes this lock for a long time so that csched_vcpu_yield may
been blocked for long time too, so I chooes set_bit and clear_bit.

Atomic operations using LOCK prefix (like set_bit and clear_bit) will block
all the physical cpus which excute memory access. Does this fact implies
that spin locks are more efficient when their's granularity is small?

Sorry for my poor english.


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