Re: [Xen-devel] [PATCH] xen: Send spinlock IPI to all waiters

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.02.13 at 12:10, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Fri, 2013-02-15 at 10:52 +0000, Stefan Bader wrote:
>> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
>> index 83e866d..f7a080e 100644
>> --- a/arch/x86/xen/spinlock.c
>> +++ b/arch/x86/xen/spinlock.c
>> @@ -328,7 +328,6 @@ static noinline void xen_spin_unlock_slow(struct 
> xen_spinlock *xl)
>>              if (per_cpu(lock_spinners, cpu) == xl) {
>>                      ADD_STATS(released_slow_kicked, 1);
>>                      xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
>> -                    break;
> 
> It would be more efficient to build a mask and use xen_send_IPI_mask().

In order for __xen_send_IPI_mask() to then take the list apart
again and call xen_send_IPI_one()? There's no batching
implemented currently...

Jan


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