Messages in this thread | | | Date | Fri, 21 Dec 2012 22:14:34 -0500 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 2/3] x86,smp: proportional backoff for ticket spinlocks |
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On Fri, Dec 21, 2012 at 10:07:56PM -0500, Steven Rostedt wrote: > > diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c > > index 20da354..4e44840 100644 > > --- a/arch/x86/kernel/smp.c > > +++ b/arch/x86/kernel/smp.c > > @@ -118,9 +118,11 @@ static bool smp_no_nmi_ipi = false; > > void ticket_spin_lock_wait(arch_spinlock_t *lock, struct __raw_tickets inc) > > { > > for (;;) { > > - cpu_relax(); > > - inc.head = ACCESS_ONCE(lock->tickets.head); > > + int loops = 50 * (__ticket_t)(inc.tail - inc.head); > > + while (loops--) > > + cpu_relax(); > > -ENOCOMMENT > > Please add a comment above to explain what it's doing. Don't expect > people to check change logs. Also, explain why you picked 50. >
OK, I replied here before reading patch 3 (still reviewing it). Why have this patch at all? Just to test if you broke something between this and patch 3? Or perhaps patch 3 may not get accepted? In that case, you would still need a comment.
Either explicitly state that this patch is just a stepping stone for patch 3, and will either be accepted or rejected along with patch 3. Or keep it as a stand alone patch and add comments as such. Or just get rid of it all together.
Thanks,
-- Steve
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