Re: [Xen-devel] [RFC PATCH 1/2]: hypervisor debugger

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.08.12 at 23:32, Matt Wilson <msw@xxxxxxxxxx> wrote:
> On Thu, Aug 30, 2012 at 11:23:23AM -0700, Mukesh Rathor wrote:
>> +#ifdef XEN_KDB_CONFIG
>> +#if defined(__x86_64__)
>> +        testl $1, kdb_session_begun(%rip)
>> +#else
>> +        testl $1, kdb_session_begun
>> +#endif
>> +        jnz  .Lkdb_skip_softirq
>> +#endif
> 
> Not sure if somthing like:
> 
>         cmpb  $0,kdb_session_begun(%rip)
> UNLIKELY_START(ne, kdb_session_exists)
>         jmp .Lkdb_skip_softirq
> UNLIKELY_END(ne, kdb_session_exists)
> 
> is worth it in this case, since it's just a jnz.

Clearly not, as the UNLIKELY_START() itself already expands to
a conditional branch.

Jan


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