Re: [PATCH v2 04/16] xen: credit2: pack trace data better for xentrace_format

[George Dunlap <george.dunlap@citrix.com>]

On 16/02/16 18:11, Dario Faggioli wrote:
> when tracing runstate changes, the vcpu and domain IDs
> are encoded in the lower and higher, respectively, parts
> of a 32 bits integer. When decoding a trace with
> xentrace_format, this makes it possible to display
> such events like this:
> 
> CPU0  833435853624 (+     768)  running_to_runnable [ dom:vcpu = 0x7fff0000 ]
> CPU0  833435854416 (+     792)  runnable_to_running [ dom:vcpu = 0x00000007 ]
> 
> For consistency, we should do the same when displaying
> the events coming from the Credit2 scheduler (when using
> the same tool), and to do that, we need to invert the
> order in which the fields are being put in the trace
> struct right now.
> 
> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

I was going to say, "We should change xentrace_format and xenalyze in
lockstep", but it turns out that they don't support these trace records
yet!   I must have some patches to xenalyze in a local branch somewhere
that I never upstreamed properly.

So, all is well:

Acked-by: George Dunlap <george.dunlap@citrix.com>

> ---
> Cc: George Dunlap <george.dunlap@citrix.com>
> Cc: Olaf Hering <olaf@aepfle.de>
> ---
>  xen/common/sched_credit2.c |   16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
> index 78220a7..cf40f68 100644
> --- a/xen/common/sched_credit2.c
> +++ b/xen/common/sched_credit2.c
> @@ -382,7 +382,7 @@ __update_svc_load(const struct scheduler *ops,
>  
>      {
>          struct {
> -            unsigned dom:16,vcpu:16;
> +            unsigned vcpu:16, dom:16;
>              unsigned v_avgload:32;
>          } d;
>          d.dom = svc->vcpu->domain->domain_id;
> @@ -450,7 +450,7 @@ runq_insert(const struct scheduler *ops, unsigned int cpu, struct csched2_vcpu *
>  
>      {
>          struct {
> -            unsigned dom:16,vcpu:16;
> +            unsigned vcpu:16, dom:16;
>              unsigned pos;
>          } d;
>          d.dom = svc->vcpu->domain->domain_id;
> @@ -536,7 +536,7 @@ runq_tickle(const struct scheduler *ops, unsigned int cpu, struct csched2_vcpu *
>  
>          /* TRACE */ {
>              struct {
> -                unsigned dom:16,vcpu:16;
> +                unsigned vcpu:16, dom:16;
>                  unsigned credit;
>              } d;
>              d.dom = cur->vcpu->domain->domain_id;
> @@ -561,9 +561,9 @@ tickle:
>  
>      /* TRACE */ {
>          struct {
> -            unsigned cpu:8;
> +            unsigned cpu:16, pad:16;
>          } d;
> -        d.cpu = ipid;
> +        d.cpu = ipid; d.pad = 0;
>          trace_var(TRC_CSCHED2_TICKLE, 0,
>                    sizeof(d),
>                    (unsigned char *)&d);
> @@ -634,7 +634,7 @@ static void reset_credit(const struct scheduler *ops, int cpu, s_time_t now,
>  
>          /* TRACE */ {
>              struct {
> -                unsigned dom:16,vcpu:16;
> +                unsigned vcpu:16, dom:16;
>                  unsigned credit_start, credit_end;
>                  unsigned multiplier;
>              } d;
> @@ -683,7 +683,7 @@ void burn_credits(struct csched2_runqueue_data *rqd, struct csched2_vcpu *svc, s
>      /* TRACE */
>      {
>          struct {
> -            unsigned dom:16,vcpu:16;
> +            unsigned vcpu:16, dom:16;
>              unsigned credit;
>              int delta;
>          } d;
> @@ -812,7 +812,7 @@ __runq_assign(struct csched2_vcpu *svc, struct csched2_runqueue_data *rqd)
>      /* TRACE */
>      {
>          struct {
> -            unsigned dom:16,vcpu:16;
> +            unsigned vcpu:16, dom:16;
>              unsigned rqi:16;
>          } d;
>          d.dom = svc->vcpu->domain->domain_id;
>