On 11/01/2017 06:01 PM, Boris Ostrovsky wrote:
> On 11/01/2017 04:58 PM, Waiman Long wrote:
>> +/* TODO: To be removed in a future kernel version */
>> static __init int xen_parse_nopvspin(char *arg)
>> {
>> - xen_pvspin = false;
>> + pr_warn("xen_nopvspin is deprecated, replace it with \"pvlock_type=queued\"!\n");
>> + if (!pv_spinlock_type)
>> + pv_spinlock_type = locktype_queued;
> Since we currently end up using unfair locks and because you are
> deprecating xen_nopvspin I wonder whether it would be better to set this
> to locktype_unfair so that current behavior doesn't change. (Sorry, I
> haven't responded to your earlier message before you posted this). Juergen?
I think the latest patch from Juergen in tip is to use native qspinlock
when xen_nopvspin is specified. Right? That is why I made the current
choice. I can certainly change to unfair if it is what you guys want.
> I am also not sure I agree with making pv_spinlock an enum *and* a
> bitmask at the same time. I understand that it makes checks easier but I
> think not assuming a value or a pattern would be better, especially
> since none of the uses is on a critical path.
>
> (For example, !pv_spinlock_type is the same as locktype_auto, which is
> defined but never used)
OK, I will take out the enum and make explicit use of locktype_auto.
Cheers,
Longman
