Re: [igt-dev] [PATCH i-g-t 01/21] scripts/trace.pl: Fix after intel_engine_notify removal

Chris Wilson
2019-05-10T12:33:04Z

Quoting Tvrtko Ursulin (2019-05-08 13:10:38)
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> After the removal of engine global seqnos and the corresponding
> intel_engine_notify tracepoints the script needs to be adjusted to cope
> with the new state of things.
>
> To keep working it switches over using the dma_fence:dma_fence_signaled:
> tracepoint and keeps one extra internal map to connect the ctx-seqno pairs
> with engines.
>
> It also needs to key the completion events on the full engine/ctx/seqno
> tokens, and adjust correspondingly the timeline sorting logic.
>
> v2:
> * Do not use late notifications (received after context complete) when
> splitting up coalesced requests. They are now much more likely and can
> not be used.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
> scripts/trace.pl | 82 ++++++++++++++++++++++++------------------------
> 1 file changed, 41 insertions(+), 41 deletions(-)
>
> diff --git a/scripts/trace.pl b/scripts/trace.pl
> index 18f9f3b18396..95dc3a645e8e 100755
> --- a/scripts/trace.pl
> +++ b/scripts/trace.pl
> @@ -27,7 +27,8 @@ use warnings;
> use 5.010;
>
> my $gid = 0;
> -my (%db, %queue, %submit, %notify, %rings, %ctxdb, %ringmap, %reqwait, %ctxtimelines);
> +my (%db, %queue, %submit, %notify, %rings, %ctxdb, %ringmap, %reqwait,
> + %ctxtimelines, %ctxengines);
> my @freqs;

So what's ctxengines? Or rings for that matter?

I take it ctxengines is really the last engine which we saw this context
execute on?

>
> my $max_items = 3000;
> @@ -66,7 +67,7 @@ Notes:
> i915:i915_request_submit, \
> i915:i915_request_in, \
> i915:i915_request_out, \
> - i915:intel_engine_notify, \
> + dma_fence:dma_fence_signaled, \
> i915:i915_request_wait_begin, \
> i915:i915_request_wait_end \
> [command-to-be-profiled]
> @@ -161,7 +162,7 @@ sub arg_trace
> 'i915:i915_request_submit',
> 'i915:i915_request_in',
> 'i915:i915_request_out',
> - 'i915:intel_engine_notify',
> + 'dma_fence:dma_fence_signaled',
> 'i915:i915_request_wait_begin',
> 'i915:i915_request_wait_end' );
>
> @@ -312,13 +313,6 @@ sub db_key
> return $ring . '/' . $ctx . '/' . $seqno;
> }
>
> -sub global_key
> -{
> - my ($ring, $seqno) = @_;
> -
> - return $ring . '/' . $seqno;
> -}
> -
> sub sanitize_ctx
> {
> my ($ctx, $ring) = @_;
> @@ -419,6 +413,8 @@ while (<>) {
> $req{'ring'} = $ring;
> $req{'seqno'} = $seqno;
> $req{'ctx'} = $ctx;
> + die if exists $ctxengines{$ctx} and $ctxengines{$ctx} ne $ring;
> + $ctxengines{$ctx} = $ring;
> $ctxtimelines{$ctx . '/' . $ring} = 1;
> $req{'name'} = $ctx . '/' . $seqno;
> $req{'global'} = $tp{'global'};
> @@ -429,16 +425,29 @@ while (<>) {
> $ringmap{$rings{$ring}} = $ring;
> $db{$key} = \%req;
> } elsif ($tp_name eq 'i915:i915_request_out:') {
> - my $gkey = global_key($ring, $tp{'global'});
> + my $gkey;
> +

# Must be paired with a previous i915_request_in
> + die unless exists $ctxengines{$ctx};

I'd suggest next unless, because there's always a change the capture is
started part way though someone's workload.

> + $gkey = db_key($ctxengines{$ctx}, $ctx, $seqno);
> +
> + if ($tp{'completed?'}) {
> + die unless exists $db{$key};
> + die unless exists $db{$key}->{'start'};
> + die if exists $db{$key}->{'end'};
> +
> + $db{$key}->{'end'} = $time;
> + $db{$key}->{'notify'} = $notify{$gkey}
> + if exists $notify{$gkey};

Hmm. With preempt-to-busy, a request can complete when we are no longer
tracking it (it completes before we preempt it).

They will still get the schedule-out tracepoint, but marked as
incomplete, and there will be a signaled tp later before we try and
resubmit.

> + } else {
> + delete $db{$key};
> + }
> + } elsif ($tp_name eq 'dma_fence:dma_fence_signaled:') {
> + my $gkey;
>
> - die unless exists $db{$key};
> - die unless exists $db{$key}->{'start'};
> - die if exists $db{$key}->{'end'};
> + die unless exists $ctxengines{$tp{'context'}};
>
> - $db{$key}->{'end'} = $time;
> - $db{$key}->{'notify'} = $notify{$gkey} if exists $notify{$gkey};
> - } elsif ($tp_name eq 'i915:intel_engine_notify:') {
> - my $gkey = global_key($ring, $seqno);
> + $gkey = db_key($ctxengines{$tp{'context'}}, $tp{'context'}, $tp{'seqno'});
>
> $notify{$gkey} = $time unless exists $notify{$gkey};
> } elsif ($tp_name eq 'i915:intel_gpu_freq_change:') {
> @@ -452,7 +461,7 @@ while (<>) {
> # find the largest seqno to be used for timeline sorting purposes.
> my $max_seqno = 0;
> foreach my $key (keys %db) {
> - my $gkey = global_key($db{$key}->{'ring'}, $db{$key}->{'global'});
> + my $gkey = db_key($db{$key}->{'ring'}, $db{$key}->{'ctx'}, $db{$key}->{'seqno'});
>
> die unless exists $db{$key}->{'start'};
>
> @@ -478,14 +487,13 @@ my $key_count = scalar(keys %db);
>
> my %engine_timelines;
>
> -sub sortEngine {
> - my $as = $db{$a}->{'global'};
> - my $bs = $db{$b}->{'global'};
> +sub sortStart {
> + my $as = $db{$a}->{'start'};
> + my $bs = $db{$b}->{'start'};
> my $val;
>
> $val = $as <=> $bs;
> -
> - die if $val == 0;
> + $val = $a cmp $b if $val == 0;
>
> return $val;
> }
> @@ -497,9 +505,7 @@ sub get_engine_timeline {
> return $engine_timelines{$ring} if exists $engine_timelines{$ring};
>
> @timeline = grep { $db{$_}->{'ring'} eq $ring } keys %db;
> - # FIXME seqno restart
> - @timeline = sort sortEngine @timeline;
> -
> + @timeline = sort sortStart @timeline;
> $engine_timelines{$ring} = \@timeline;
>
> return \@timeline;
> @@ -561,20 +567,10 @@ foreach my $gid (sort keys %rings) {
> $db{$key}->{'no-notify'} = 1;
> }
> $db{$key}->{'end'} = $end;
> + $db{$key}->{'notify'} = $end if $db{$key}->{'notify'} > $end;
> }
> }
>
> -sub sortStart {
> - my $as = $db{$a}->{'start'};
> - my $bs = $db{$b}->{'start'};
> - my $val;
> -
> - $val = $as <=> $bs;
> - $val = $a cmp $b if $val == 0;
> -
> - return $val;
> -}
> -
> my $re_sort = 1;
> my @sorted_keys;
>
> @@ -670,9 +666,13 @@ if ($correct_durations) {
> next unless exists $db{$key}->{'no-end'};
> last if $pos == $#{$timeline};
>
> - # Shift following request to start after the current one
> + # Shift following request to start after the current
> + # one, but only if that wouldn't make it zero duration,
> + # which would indicate notify arrived after context
> + # complete.
> $next_key = ${$timeline}[$pos + 1];
> - if (exists $db{$key}->{'notify'}) {
> + if (exists $db{$key}->{'notify'} and
> + $db{$key}->{'notify'} < $db{$key}->{'end'}) {
> $db{$next_key}->{'engine-start'} = $db{$next_key}->{'start'};
> $db{$next_key}->{'start'} = $db{$key}->{'notify'};
> $re_sort = 1;
> @@ -750,9 +750,9 @@ foreach my $gid (sort keys %rings) {
> # Extract all GPU busy intervals and sort them.
> foreach my $key (@sorted_keys) {
> next unless $db{$key}->{'ring'} eq $ring;
> + die if $db{$key}->{'start'} > $db{$key}->{'end'};

Heh, we're out of luck if we want to trace across seqno wraparound.

It makes enough sense,
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris