Clamp fakePixels to maxFakesInModule

[fwyzard]

PR description:

After running the Pixel digi morphing algorithm, clamp fakePixels to maxFakesInModule to avoid overflowing the histogram container.

PR validation:

Run on top of the reproducer at #49125 without any crashes.

If this PR is a backport please specify the original PR and why you need to backport that PR. If this PR will be backported please specify to which release cycle the backport is meant for:

To be backported to 15.1.x and 15.0.x.

[fwyzard]

type bugfix

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49142/46429

• There are other open Pull requests which might conflict with changes you have proposed:
  • File RecoLocalTracker/SiPixelClusterizer/plugins/alpaka/PixelClustering.h modified in PR(s): Pixelimage morphing #48343

[cmsbuild]

A new Pull Request was created by @fwyzard for master.

It involves the following packages:

• RecoLocalTracker/SiPixelClusterizer (reconstruction)

@cmsbuild, @jfernan2, @mandrenguyen can you please review it and eventually sign? Thanks.
@GiacomoSguazzoni, @VinInn, @VourMa, @dkotlins, @elusian, @felicepantaleo, @ferencek, @gpetruc, @mmasciov, @mmusich, @mroguljic, @mtosi, @rovere, @threus, @tsusa, @tvami this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

[fwyzard]

enable gpu

[fwyzard]

please test

[ftenchini]

+1

[cmsbuild]

+1

Size: This PR adds an extra 28KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5f5be2/48632/summary.html
COMMIT: 824875b
CMSSW: CMSSW_16_0_X_2025-10-12-2300/el8_amd64_gcc13
Additional Tests: GPU,AMD_MI300X,AMD_W7900,NVIDIA_H100,NVIDIA_L40S,NVIDIA_T4
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/49142/48632/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 3 lines to the logs
• Reco comparison results: 6 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3940073
• DQMHistoTests: Total failures: 41
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3940012
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 50 files compared)
• Checked 218 log files, 188 edm output root files, 51 DQM output files
• TriggerResults: no differences found

AMD_MI300X Comparison Summary

Summary:

• You potentially added 1 lines to the logs
• Reco comparison results: 252 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 146621
• DQMHistoTests: Total failures: 27163
• DQMHistoTests: Total nulls: 5
• DQMHistoTests: Total successes: 119453
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

AMD_W7900 Comparison Summary

Summary:

• You potentially removed 5 lines from the logs
• Reco comparison results: 224 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 146621
• DQMHistoTests: Total failures: 33164
• DQMHistoTests: Total nulls: 10
• DQMHistoTests: Total successes: 113447
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: found differences in 1 / 10 workflows

NVIDIA_H100 Comparison Summary

Summary:

• You potentially removed 1 lines from the logs
• Reco comparison results: 262 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 146621
• DQMHistoTests: Total failures: 26736
• DQMHistoTests: Total nulls: 9
• DQMHistoTests: Total successes: 119876
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

NVIDIA_L40S Comparison Summary

Summary:

• You potentially added 3 lines to the logs
• Reco comparison results: 236 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 146621
• DQMHistoTests: Total failures: 23809
• DQMHistoTests: Total nulls: 8
• DQMHistoTests: Total successes: 122804
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

NVIDIA_T4 Comparison Summary

Summary:

• You potentially removed 1 lines from the logs
• Reco comparison results: 248 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 146621
• DQMHistoTests: Total failures: 27102
• DQMHistoTests: Total nulls: 11
• DQMHistoTests: Total successes: 119508
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

[pietroGru]

why not once_per_block?

[fwyzard]

this

if (fakePixels > maxFakesInModule) {
  if (alpaka::once_per_block(acc)) {
    fakePixels = maxFakesInModule;
  }
  alpaka::syncBlockThreads(acc);
}

would indeed be equivalent.
But it's one extra line of code 🤷🏻‍♂️

[fwyzard]

Note that both approaches are fine because they are right after a alpaka::syncBlockThreads(acc);

[ftenchini]

@cms-sw/reconstruction-l2 could you please review this as well as its backport #49144?
They are needed in a patch for data-taking.

[jfernan2]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will be automatically merged.