llvm dev - Apr 2016 - FW: RFC: LNT/Test-suite support for custom metrics and test parameterization

On 22 Apr 2016, at 11:14, Mehdi Amini <mehdi.amini at
apple.com<mailto:mehdi.amini at apple.com>> wrote:


On Apr 22, 2016, at 12:45 AM, Kristof Beyls via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:


On 21 Apr 2016, at 17:44, Sergey Yakoushkin <sergey.yakoushkin at
gmail.com<mailto:sergey.yakoushkin at gmail.com>> wrote:

Hi Kristof,

       The way we use LNT, we would run different configuration (e.g. -O3 vs
-Os) as different "machines" in LNT's model.

O2/O3 is indeed bad example. We're also using different machines for Os/O3 -
such parameters apply to all tests and we don't propose major changes.
Elena was only extending LNT interface a bit to ease LLVM-testsuite execution
with different compiler or HW flags.

Oh I see, this boils down to extending the lnt runtest interface to be able to
specify a set of configurations, rather than a single configuration and making
sure configurations get submitted under different machine names? We kick off the
different configuration runs through a script invoking lnt runtest multiple
times. I don't see a big problem with extending the lnt runtest interface to
do this, assuming it doesn't break the underlying concepts assumed
throughout
LNT. Maybe the only downside is that this will add even more command line
options to lnt runtest, which already has a lot (too many?) command line
options.

Maybe some changes are required to analyze and compare metrics between
"machines": e.g. code size/performance between Os/O2/O3.
Do you perform such comparisons?

We typically do these kinds of comparisons when we test our patches pre-commit,
i.e. comparing for example '-O3' with '-O3 'mllvm
-enable-my-new-pass'.
To stick with the LNT concepts, tests enabling new passes are stored as a
different "machine".
The only way I know to be able to do a comparison between runs on 2 different
"machine"s is to manually edit the URL for run vs run comparison
and fill in the runids of the 2 runs you want to compare.
For example, the following URL is a comparison of green-dragon-07-x86_64-O3-flto
vs green-dragon-06-x86_64-O0-g on the public
llvm.org/perf<http://llvm.org/perf> server:
http://llvm.org/perf/db_default/v4/nts/70644?compare_to=70634
I had to manually look up and fill in the run ids 70644 and 70634.
It would be great if there was a better way to be able to do these kind of
comparisons - i.e. not having to manually fill in run ids, but having a webui to
easily find and pick the runs you want to compare.
(As an aside: I find it intriguing that the URL above suggests that there are
quite a few cases where "-O0 -g" produces faster code than "-O3
-flto").

Can you be more explicit which ones? I don't see any regression (other than
compared to the baseline, or on the compile time).

--
Mehdi

D'Oh! I was misinterpreting the compile time differences as execution time
differences. Indeed, there is no unexpected result in there.
Sorry for the noise!

Kristof

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Hi Sergey, Elena,

Firstly, thanks for this RFC. It's great to see more people actively using
and modifying LNT and the test metrics support in general is rather weak
currently.

Metrics
-------

I agree with Daniel and Kristof that your proposed schema changes have the
potential to make many queries extremely slow. Certainly for the metrics
enhancements, I don't see a reason why we need such a radical change in
schema.

To add custom metrics on the fly, we need to change the schema for the
Sample table. Currently this consists of a column for each metric, but
actually we never ever query those metric values. We never query for
example for "all failing tests in a run" - when we do analyses we use
the
ComparisonResult class which reads *all* samples from the database for a
run and performs the analysis entirely in Python.

Therefore, having a semi-structured format where some fields are
first-class columns and the rest are in a JSON-encoded BLOB (as Daniel
suggests) seems totally acceptable. There is certainly an argument now that
we're using the wrong backend storage solution and that a key-value store
might be more suitable, but that's a very invasive change and I don't
think
we've reached the point where we need to force a move from the simplicity
of SQLite.

Adding an extra BLOB column would be easy - there would just need to be
logic in testsuitedb.py for reading and writing it - the Sample model class
would expose the JSON-encoded fields as normal python fields so the rest of
LNT would be isolated from this change.

But I think this is a small detail compared to the bigger problem of how to
effectively *display* all this new data. Currently every new metric gets
its own separate table in the report/run views, and this does not scale
well at all.

I think we need some more concepts in the metric system to make it
scaleable:

  * What "attribute" of the test is this metric measuring? For
example,
both "exec_time" and "score" measure the same attribute;
performance of the
generated code. It's superfluous to have them displayed in separate tables.
However mem_size and compile_time both measure completely different aspects
of the test.
  * Is this metric useful to display at the top level? or should it only be
exposed when more data about a test result is requested?
    * An example of this is the pass statistics. I don't want my daily
report view cluttered by the time spent in register allocation for every
test! OK, this is useful information when debugging a problem, but it
should be available when requested rather than by default.

An example of why we need the above is your screenshots in your google doc.
I'm looking at the last screenshot, and it's incredibly difficult to
read
and get useful information out of.

I'd also suggest that if we're adding many more metrics to a test, we
should create a "test sample information" page that the test link goes
to
instead of just the graph. This page could contain all counter/metric data,
historic sparklines, the full graph and profiling links.

Cheers,

James

On Fri, 22 Apr 2016 at 10:17 Kristof Beyls via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
>
> On 22 Apr 2016, at 11:14, Mehdi Amini <mehdi.amini at apple.com>
wrote:
>
>
> On Apr 22, 2016, at 12:45 AM, Kristof Beyls via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>
> On 21 Apr 2016, at 17:44, Sergey Yakoushkin <sergey.yakoushkin at
gmail.com>
> wrote:
>
> Hi Kristof,
>
>        The way we use LNT, we would run different configuration (e.g. -O3
> vs -Os) as different "machines" in LNT's model.
>
> O2/O3 is indeed bad example. We're also using different machines for
Os/O3
> - such parameters apply to all tests and we don't propose major
changes.
> Elena was only extending LNT interface a bit to ease LLVM-testsuite
> execution with different compiler or HW flags.
>
>
> Oh I see, this boils down to extending the lnt runtest interface to be
> able to specify a set of configurations, rather than a single configuration
> and making
> sure configurations get submitted under different machine names? We kick
> off the different configuration runs through a script invoking lnt runtest
> multiple
> times. I don't see a big problem with extending the lnt runtest
interface
> to do this, assuming it doesn't break the underlying concepts assumed
> throughout
> LNT. Maybe the only downside is that this will add even more command line
> options to lnt runtest, which already has a lot (too many?) command line
> options.
>
> Maybe some changes are required to analyze and compare metrics between
> "machines": e.g. code size/performance between Os/O2/O3.
> Do you perform such comparisons?
>
>
> We typically do these kinds of comparisons when we test our patches
> pre-commit, i.e. comparing for example '-O3' with '-O3
'mllvm
> -enable-my-new-pass'.
> To stick with the LNT concepts, tests enabling new passes are stored as a
> different "machine".
> The only way I know to be able to do a comparison between runs on 2
> different "machine"s is to manually edit the URL for run vs run
comparison
> and fill in the runids of the 2 runs you want to compare.
> For example, the following URL is a comparison of
> green-dragon-07-x86_64-O3-flto vs green-dragon-06-x86_64-O0-g on the public
>  llvm.org/perf server:
> http://llvm.org/perf/db_default/v4/nts/70644?compare_to=70634
> I had to manually look up and fill in the run ids 70644 and 70634.
> It would be great if there was a better way to be able to do these kind of
> comparisons - i.e. not having to manually fill in run ids, but having a
> webui to easily find and pick the runs you want to compare.
> (As an aside: I find it intriguing that the URL above suggests that there
> are quite a few cases where "-O0 -g" produces faster code than
"-O3 -flto").
>
>
> Can you be more explicit which ones? I don't see any regression (other
> than compared to the baseline, or on the compile time).
>
> --
> Mehdi
>
>
> D'Oh! I was misinterpreting the compile time differences as execution
time
> differences. Indeed, there is no unexpected result in there.
> Sorry for the noise!
>
> Kristof
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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From: Elena Lepilkina
Sent: Monday, April 25, 2016 2:33 PM
To: 'James Molloy' <james at jamesmolloy.co.uk>; Kristof Beyls
<Kristof.Beyls at arm.com>; Mehdi Amini <mehdi.amini at apple.com>
Cc: nd <nd at arm.com>; Matthias Braun <matze at braunis.de>
Subject: RE: [llvm-dev] RFC: LNT/Test-suite support for custom metrics and test
parameterization

Hi everyone,

Thank you for your answer. BLOB format adds some more actions for working with
metrics. We know that ComparisonResult class makes analysis work. But it gets
all metrics by request from database, we will need additional time for work with
fields during analysis in ComparisonResult class. May be it will be better to do
one Sample table for each testsuite, as it was suggested before. It should be
more quickly, shouldn’t it? Moreover, next wished LNT changes will need getting
some metrics separately and BLOB format will add some delay in time for queries.

As we see now problem of performance is actual, because time for rendering graph
page is about 3 minutes.
[cid:image001.png at 01D19EFA.6E5F0A70]
So maybe it will be better to start working with NoSql databases? I made a small
prototype with TestSuite, TestSuiteFields, Test, Run and Sample tables for
getting time metrics. It works quickly. And using NoSQL helps solve problems
with  different fields for samples metrics fields. Then it will be possible to
store different metrics for different testsuites in one table.
What do you think about this proposal?
I used MongoDB, but I know that there is NoSQL extension for PostgresSQL with
JSONB fields which are more
effective than JSON-encoded BLOB, because it can be included in queries very
simply and let use indexes.

About proposal that not all metrics should be shown. It can be added as a field
in JSON in .fields file, which describes fields getted from test-suite. To see
other metrics user should choose them with checkboxes in view options. Will be
this solution suitable?
We can make as you wrote
“I'd also suggest that if we're adding many more metrics to a test, we
should create a "test sample information" page that the test link goes
to instead of just the graph. This page could contain all counter/metric data,
historic sparklines, the full graph and profiling links.
”
But the render time of this page will be too great because of graph render time.
In my opinion, some users wouldn’t like to wait so long for see some additional
metrics.

Thanks for your suggestions,

Elena.
From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of James
Molloy via llvm-dev
Sent: Monday, April 25, 2016 12:43 PM
To: Kristof Beyls <Kristof.Beyls at arm.com<mailto:Kristof.Beyls at
arm.com>>; Mehdi Amini <mehdi.amini at apple.com<mailto:mehdi.amini
at apple.com>>
Cc: llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at
lists.llvm.org>>; nd <nd at arm.com<mailto:nd at arm.com>>;
Matthias Braun <matze at braunis.de<mailto:matze at braunis.de>>
Subject: Re: [llvm-dev] RFC: LNT/Test-suite support for custom metrics and test
parameterization

Hi Sergey, Elena,

Firstly, thanks for this RFC. It's great to see more people actively using
and modifying LNT and the test metrics support in general is rather weak
currently.

Metrics
-------

I agree with Daniel and Kristof that your proposed schema changes have the
potential to make many queries extremely slow. Certainly for the metrics
enhancements, I don't see a reason why we need such a radical change in
schema.

To add custom metrics on the fly, we need to change the schema for the Sample
table. Currently this consists of a column for each metric, but actually we
never ever query those metric values. We never query for example for "all
failing tests in a run" - when we do analyses we use the ComparisonResult
class which reads *all* samples from the database for a run and performs the
analysis entirely in Python.

Therefore, having a semi-structured format where some fields are first-class
columns and the rest are in a JSON-encoded BLOB (as Daniel suggests) seems
totally acceptable. There is certainly an argument now that we're using the
wrong backend storage solution and that a key-value store might be more
suitable, but that's a very invasive change and I don't think we've
reached the point where we need to force a move from the simplicity of SQLite.

Adding an extra BLOB column would be easy - there would just need to be logic in
testsuitedb.py for reading and writing it - the Sample model class would expose
the JSON-encoded fields as normal python fields so the rest of LNT would be
isolated from this change.

But I think this is a small detail compared to the bigger problem of how to
effectively *display* all this new data. Currently every new metric gets its own
separate table in the report/run views, and this does not scale well at all.

I think we need some more concepts in the metric system to make it scaleable:

  * What "attribute" of the test is this metric measuring? For
example, both "exec_time" and "score" measure the same
attribute; performance of the generated code. It's superfluous to have them
displayed in separate tables. However mem_size and compile_time both measure
completely different aspects of the test.
  * Is this metric useful to display at the top level? or should it only be
exposed when more data about a test result is requested?
    * An example of this is the pass statistics. I don't want my daily
report view cluttered by the time spent in register allocation for every test!
OK, this is useful information when debugging a problem, but it should be
available when requested rather than by default.

An example of why we need the above is your screenshots in your google doc.
I'm looking at the last screenshot, and it's incredibly difficult to
read and get useful information out of.

I'd also suggest that if we're adding many more metrics to a test, we
should create a "test sample information" page that the test link goes
to instead of just the graph. This page could contain all counter/metric data,
historic sparklines, the full graph and profiling links.

Cheers,

James

On Fri, 22 Apr 2016 at 10:17 Kristof Beyls via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

On 22 Apr 2016, at 11:14, Mehdi Amini <mehdi.amini at
apple.com<mailto:mehdi.amini at apple.com>> wrote:


On Apr 22, 2016, at 12:45 AM, Kristof Beyls via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:


On 21 Apr 2016, at 17:44, Sergey Yakoushkin <sergey.yakoushkin at
gmail.com<mailto:sergey.yakoushkin at gmail.com>> wrote:

Hi Kristof,

       The way we use LNT, we would run different configuration (e.g. -O3 vs
-Os) as different "machines" in LNT's model.

O2/O3 is indeed bad example. We're also using different machines for Os/O3 -
such parameters apply to all tests and we don't propose major changes.
Elena was only extending LNT interface a bit to ease LLVM-testsuite execution
with different compiler or HW flags.

Oh I see, this boils down to extending the lnt runtest interface to be able to
specify a set of configurations, rather than a single configuration and making
sure configurations get submitted under different machine names? We kick off the
different configuration runs through a script invoking lnt runtest multiple
times. I don't see a big problem with extending the lnt runtest interface to
do this, assuming it doesn't break the underlying concepts assumed
throughout
LNT. Maybe the only downside is that this will add even more command line
options to lnt runtest, which already has a lot (too many?) command line
options.

Maybe some changes are required to analyze and compare metrics between
"machines": e.g. code size/performance between Os/O2/O3.
Do you perform such comparisons?

We typically do these kinds of comparisons when we test our patches pre-commit,
i.e. comparing for example '-O3' with '-O3 'mllvm
-enable-my-new-pass'.
To stick with the LNT concepts, tests enabling new passes are stored as a
different "machine".
The only way I know to be able to do a comparison between runs on 2 different
"machine"s is to manually edit the URL for run vs run comparison
and fill in the runids of the 2 runs you want to compare.
For example, the following URL is a comparison of green-dragon-07-x86_64-O3-flto
vs green-dragon-06-x86_64-O0-g on the public
llvm.org/perf<http://llvm.org/perf> server:
http://llvm.org/perf/db_default/v4/nts/70644?compare_to=70634
I had to manually look up and fill in the run ids 70644 and 70634.
It would be great if there was a better way to be able to do these kind of
comparisons - i.e. not having to manually fill in run ids, but having a webui to
easily find and pick the runs you want to compare.
(As an aside: I find it intriguing that the URL above suggests that there are
quite a few cases where "-O0 -g" produces faster code than "-O3
-flto").

Can you be more explicit which ones? I don't see any regression (other than
compared to the baseline, or on the compile time).

--
Mehdi

D'Oh! I was misinterpreting the compile time differences as execution time
differences. Indeed, there is no unexpected result in there.
Sorry for the noise!

Kristof

_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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