lkml.org 
[lkml]   [2014]   [Oct]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 06/12] perf/x86: implement cross-HT corruption bug workaround
On Wed, Oct 22, 2014 at 02:31:51PM +0200, Jiri Olsa wrote:
> On Thu, Oct 09, 2014 at 06:34:40PM +0200, Stephane Eranian wrote:
> > From: Maria Dimakopoulou <maria.n.dimakopoulou@gmail.com>
>
> SNIP
>
> > +static struct event_constraint *
> > +intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event,
> > + int idx, struct event_constraint *c)
> > +{
> > + struct event_constraint *cx;
> > + struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs;
> > + struct intel_excl_states *xl, *xlo;
> > + int is_excl, i;
>
> SNIP
>
> > + /*
> > + * Modify static constraint with current dynamic
> > + * state of thread
> > + *
> > + * EXCLUSIVE: sibling counter measuring exclusive event
> > + * SHARED : sibling counter measuring non-exclusive event
> > + * UNUSED : sibling counter unused
> > + */
> > + for_each_set_bit(i, cx->idxmsk, X86_PMC_IDX_MAX) {
> > + /*
> > + * exclusive event in sibling counter
> > + * our corresponding counter cannot be used
> > + * regardless of our event
> > + */
> > + if (xl->state[i] == INTEL_EXCL_EXCLUSIVE)
> > + __clear_bit(i, cx->idxmsk);
>
> if we want to check sibling counter, shouldn't we check xlo->state[i] instead? like
>
> if (xlo->state[i] == INTEL_EXCL_EXCLUSIVE)
> __clear_bit(i, cx->idxmsk);
>
>
> and also in condition below?

any comment on this? I'm curious, because it'd enlighten me
on how this is supposed to work ;-)

I dont understand why you update the sibling's counter state instead
of the current cpuc->excl_thread_id HT, like in intel_commit_scheduling
while you hold lock for the current HT state

could you please comment, I must be missing something

thanks,
jirka


\
 
 \ /
  Last update: 2014-10-23 10:01    [W:0.164 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site