This is a revision of my earlier patch to add working set information to
the gcov program summary based on discussions between Honza, David and I
and approved with changes by Honza in this earlier thread on the first patch:
http://gcc.gnu.org/ml/gcc-patches/2012-07/msg01412.html
I plan to commit
> +{
> + cs_prg->num = cs_tprg->num;
> + /* Allocate the working set array for the merged summary.
> */
> + if (ws_cnt)
> +{
> + cs_prg->working_set_count = ws_cnt;
> +
On Sat, Aug 18, 2012 at 1:19 AM, Jan Hubicka wrote:
>
> > +{
> > + cs_prg->num = cs_tprg->num;
> > + /* Allocate the working set array for the merged
> > summary. */
> > + if (ws_cnt)
> > +{
> > +
On Sun, Aug 19, 2012 at 9:59 PM, Teresa Johnson wrote:
> On Sat, Aug 18, 2012 at 1:19 AM, Jan Hubicka wrote:
>>
>> > +{
>> > + cs_prg->num = cs_tprg->num;
>> > + /* Allocate the working set array for the merged
>> > summary. */
>> > +
> Well, it should store the largest working set in BBs, or one that came
> from a much longer run. But I see the issue you are pointing out. The
> num_counters (the number of hot bbs) should be reasonable, as the
> total number of BBs is the same between all runs, and I want to show
> the largest o
On Mon, Aug 20, 2012 at 2:48 AM, Jan Hubicka wrote:
>> Well, it should store the largest working set in BBs, or one that came
>> from a much longer run. But I see the issue you are pointing out. The
>> num_counters (the number of hot bbs) should be reasonable, as the
>> total number of BBs is the
On Mon, Aug 20, 2012 at 11:48 AM, Jan Hubicka wrote:
>> The summary merging in coverage.c confuses me a bit as it seems to be
>> handling the case when there are multiple program summaries in a
>> single gcda file. When would this happen? It looks like the merge
>> handling in libgcov should alway
>
> So I definitely preffer 2 or 3 over 1. David has experience with 3. How well
> does
> it work for LIPO?
>
This (lack of locking, races) is not a new problem. There is no
synchronization in libgcov for profile update/merge at both thread and
process level. Thread level data races leads to inco
> If this approach seems like it is feasible, then we could stick with
> the current approach of emitting the working set array in the summary,
> mitigating it somewhat by doing the sum_all based scaling of the
> counter values, then in a follow on patch restructure the merging code
> to delay the
On Mon, Aug 20, 2012 at 8:35 AM, Steven Bosscher wrote:
> On Mon, Aug 20, 2012 at 11:48 AM, Jan Hubicka wrote:
>>> The summary merging in coverage.c confuses me a bit as it seems to be
>>> handling the case when there are multiple program summaries in a
>>> single gcda file. When would this happe
On Mon, Aug 20, 2012 at 7:44 PM, Teresa Johnson wrote:
> But
> the code in coverage.c is dealing with a single gcda file containing
> multiple program summaries. Is there code somewhere that will cause
> this to happen?
Not that I know of, no.
(There are enhancement requests for this, see e.g. PR
Xinliang David Li writes:
>
> Process level synchronization problems can happen when two processes
> (running the instrumented binary) exit at the same time. The
> updated/merged counters from one process may be overwritten by another
> process -- this is true for both counter data and summary dat
I was mistaken here -- gcov_open actually uses locking via fcntl
interface -- so we do need to find a way to solve the summary update
synchronization problem when it is separate out of the per-file update
loop.
David
On Mon, Aug 20, 2012 at 12:03 PM, Andi Kleen wrote:
> Xinliang David Li writes
> Xinliang David Li writes:
> >
> > Process level synchronization problems can happen when two processes
> > (running the instrumented binary) exit at the same time. The
> > updated/merged counters from one process may be overwritten by another
> > process -- this is true for both counter data and
On Mon, Aug 20, 2012 at 6:27 PM, Jan Hubicka wrote:
>> Xinliang David Li writes:
>> >
>> > Process level synchronization problems can happen when two processes
>> > (running the instrumented binary) exit at the same time. The
>> > updated/merged counters from one process may be overwritten by ano
> On Mon, Aug 20, 2012 at 6:27 PM, Jan Hubicka wrote:
> >> Xinliang David Li writes:
> >> >
> >> > Process level synchronization problems can happen when two processes
> >> > (running the instrumented binary) exit at the same time. The
> >> > updated/merged counters from one process may be overwr
On Mon, Aug 20, 2012 at 10:29 PM, Jan Hubicka wrote:
>> On Mon, Aug 20, 2012 at 6:27 PM, Jan Hubicka wrote:
>> >> Xinliang David Li writes:
>> >> >
>> >> > Process level synchronization problems can happen when two processes
>> >> > (running the instrumented binary) exit at the same time. The
>>
>
> This is useful for large applications with a long tail. The
> instruction working set for those applications are very large, and
> inliner and unroller need to be aware of that and good heuristics can
> be developed to throttle aggressive code bloat transformations. For
> inliner, it is kind o
On Mon, Aug 20, 2012 at 11:33 PM, Jan Hubicka wrote:
>>
>> This is useful for large applications with a long tail. The
>> instruction working set for those applications are very large, and
>> inliner and unroller need to be aware of that and good heuristics can
>> be developed to throttle aggressi
> Teresa has done some tunings for the unroller so far. The inliner
> tuning is the next step.
>
> >
> > What concerns me that it is greatly inaccurate - you have no idea how many
> > instructions given counter is guarding and it can differ quite a lot. Also
> > inlining/optimization makes working
> The issue here is holding lock for all the files (that can be many) versus
> number of locks limits & possibilities for deadlocking (mind that updating
> may happen in different orders on the same files for different programs built
> from same objects)
lockf typically has a deadlock detector, an
On Tue, Aug 21, 2012 at 12:34 AM, Jan Hubicka wrote:
>> Teresa has done some tunings for the unroller so far. The inliner
>> tuning is the next step.
>>
>> >
>> > What concerns me that it is greatly inaccurate - you have no idea how many
>> > instructions given counter is guarding and it can diffe
> > I can go ahead with the histogram approach. There is some roundoff
> > error from the working set scaling approach that can affect different
> > merging orders as you note, although I think this only really affects the
> > small counter values. The other place where saving/merging the histogram
On Tue, Aug 21, 2012 at 6:56 PM, Jan Hubicka wrote:
>> > I can go ahead with the histogram approach. There is some roundoff
>> > error from the working set scaling approach that can affect different
>> > merging orders as you note, although I think this only really affects the
>> > small counter v
> On Tue, Aug 21, 2012 at 6:56 PM, Jan Hubicka wrote:
> >> > I can go ahead with the histogram approach. There is some roundoff
> >> > error from the working set scaling approach that can affect different
> >> > merging orders as you note, although I think this only really affects the
> >> > small
On Tue, Aug 21, 2012 at 11:18 PM, Jan Hubicka wrote:
>> On Tue, Aug 21, 2012 at 6:56 PM, Jan Hubicka wrote:
>> >> > I can go ahead with the histogram approach. There is some roundoff
>> >> > error from the working set scaling approach that can affect different
>> >> > merging orders as you note,
>
> I'm concerned about inaccuracies arising when multiple runs have
> different sizes and therefore counters are in different buckets in the
> corresponding histograms. We would end up in a situation where the
> merged histogram has more "counters" in it than there are actual
> counters in the pr
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