[SamplePGO] Support -salvage-stale-profile without probes too #86116
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@llvm/pr-subscribers-llvm-transforms Author: Krzysztof Pszeniczny (amharc) ChangesCurrently -salvage-stale-profile is a no-op if the profile is not probe-based. We observed that it can help for regular, non-probe- based profiles too: some of our internal benchmarks show 0.2-0.3% QPS improvement. There seems to be no good reason to limit this flag to only work for probe-based profiles. Full diff: https://github.com/llvm/llvm-project/pull/86116.diff 3 Files Affected:
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index 9a8040bc4b064e..8a007358b35676 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -2411,10 +2411,10 @@ void SampleProfileMatcher::runOnFunction(const Function &F) {
if (ReportProfileStaleness || PersistProfileStaleness)
recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors, nullptr);
- // Run profile matching for checksum mismatched profile, currently only
- // support for pseudo-probe.
- if (SalvageStaleProfile && FunctionSamples::ProfileIsProbeBased &&
- !ProbeManager->profileIsValid(F, *FSFlattened)) {
+ // Run profile matching for checksum mismatched profile. For probe-based
+ // profiles, run matching only when the current profile is not valid.
+ if (SalvageStaleProfile && (!FunctionSamples::ProfileIsProbeBased ||
+ !ProbeManager->profileIsValid(F, *FSFlattened))) {
// The matching result will be saved to IRToProfileLocationMap, create a new
// map for each function.
auto &IRToProfileLocationMap = getIRToProfileLocationMap(F);
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching.prof b/llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching.prof
new file mode 100644
index 00000000000000..35eb1761f38b20
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching.prof
@@ -0,0 +1,22 @@
+main:6822:0
+ 1: 0
+ 2: 614
+ 3: 614
+ 4: 603
+ 5: 0
+ 7: 631 bar:631
+ 9: 636 bar:636
+ 6: foo:1900
+ 1: 614
+ 2: 554
+ 3: 59
+ 4: 614
+ 6: 59 bar:59
+ 8: foo:1859
+ 1: 589
+ 2: 526
+ 3: 63
+ 4: 618
+ 6: 63 bar:65
+bar:2401:2401
+ 1: 2401
diff --git a/llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching.ll b/llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching.ll
new file mode 100644
index 00000000000000..f06c112b2f2cdf
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching.ll
@@ -0,0 +1,242 @@
+; REQUIRES: x86_64-linux
+; REQUIRES: asserts
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-stale-profile-matching-lto.prof --salvage-stale-profile -S --debug-only=sample-profile,sample-profile-impl 2>&1 | FileCheck %s
+
+
+; CHECK: Run stale profile matching for main
+
+; CHECK: Location is matched from 1 to 1
+; CHECK: Location is matched from 2 to 2
+; CHECK: Location is matched from 4 to 4
+; CHECK: Location is matched from 6 to 6
+; CHECK: Location is matched from 7 to 7
+; CHECK: Location is matched from 8 to 8
+; CHECK: Location is matched from 10 to 10
+
+; CHECK: Callsite with callee:foo is matched from 12 to 6
+; CHECK: Location is rematched backwards from 7 to 1
+; CHECK: Location is rematched backwards from 8 to 2
+; CHECK: Location is rematched backwards from 10 to 4
+; CHECK: Callsite with callee:bar is matched from 13 to 7
+; CHECK: Callsite with callee:foo is matched from 14 to 8
+; CHECK: Callsite with callee:bar is matched from 15 to 9
+
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@x = internal global i32 1, align 4, !dbg !0
+
+; Function Attrs: nounwind uwtable
+define dso_local i32 @main() local_unnamed_addr #0 !dbg !49 !prof !55 {
+ call void @llvm.dbg.value(metadata i32 0, metadata !53, metadata !DIExpression()), !dbg !57
+ br label %1, !dbg !61
+
+1: ; preds = %17, %0
+ %2 = phi i32 [ 0, %0 ], [ %28, %17 ]
+ call void @llvm.dbg.value(metadata i32 %2, metadata !53, metadata !DIExpression()), !dbg !57
+ %3 = load volatile i32, ptr @x, align 4, !dbg !65, !tbaa !66
+ call void @llvm.dbg.value(metadata i32 %2, metadata !70, metadata !DIExpression()), !dbg !76
+ call void @llvm.dbg.value(metadata i32 %3, metadata !75, metadata !DIExpression()), !dbg !76
+ %4 = urem i32 %2, 10, !dbg !81
+ %5 = icmp eq i32 %4, 0, !dbg !81
+ %6 = zext i1 %5 to i32, !dbg !82
+ %7 = add nsw i32 %3, %6, !dbg !82
+ %8 = call i32 @bar(i32 noundef %7) #4, !dbg !83, !prof !84
+ %9 = load volatile i32, ptr @x, align 4, !dbg !86, !tbaa !66
+ %10 = add nsw i32 %9, %8, !dbg !86
+ store volatile i32 %10, ptr @x, align 4, !dbg !86, !tbaa !66
+ %11 = load volatile i32, ptr @x, align 4, !dbg !87, !tbaa !66
+ %12 = call i32 @bar(i32 noundef %11) #4, !dbg !88, !prof !90
+ %13 = load volatile i32, ptr @x, align 4, !dbg !91, !tbaa !66
+ %14 = add nsw i32 %13, %12, !dbg !91
+ store volatile i32 %14, ptr @x, align 4, !dbg !91, !tbaa !66
+ %15 = load volatile i32, ptr @x, align 4, !dbg !92, !tbaa !66
+ %16 = icmp slt i32 %15, 0, !dbg !94
+ br i1 %16, label %30, label %17, !dbg !95, !prof !96
+
+17: ; preds = %1
+ %18 = load volatile i32, ptr @x, align 4, !dbg !98, !tbaa !66
+ call void @llvm.dbg.value(metadata i32 %2, metadata !70, metadata !DIExpression()), !dbg !99
+ call void @llvm.dbg.value(metadata i32 %18, metadata !75, metadata !DIExpression()), !dbg !99
+ %19 = zext i1 %5 to i32, !dbg !103
+ %20 = add nsw i32 %18, %19, !dbg !103
+ %21 = call i32 @bar(i32 noundef %20) #4, !dbg !104, !prof !84
+ %22 = load volatile i32, ptr @x, align 4, !dbg !106, !tbaa !66
+ %23 = add nsw i32 %22, %21, !dbg !106
+ store volatile i32 %23, ptr @x, align 4, !dbg !106, !tbaa !66
+ %24 = load volatile i32, ptr @x, align 4, !dbg !107, !tbaa !66
+ %25 = call i32 @bar(i32 noundef %24) #4, !dbg !108, !prof !90
+ %26 = load volatile i32, ptr @x, align 4, !dbg !110, !tbaa !66
+ %27 = add nsw i32 %26, %25, !dbg !110
+ store volatile i32 %27, ptr @x, align 4, !dbg !110, !tbaa !66
+ %28 = add nuw nsw i32 %2, 1, !dbg !112
+ call void @llvm.dbg.value(metadata i32 %28, metadata !53, metadata !DIExpression()), !dbg !57
+ %29 = icmp eq i32 %28, 1000000, !dbg !114
+ br i1 %29, label %30, label %1, !dbg !61, !prof !116, !llvm.loop !117
+
+30: ; preds = %17, %1
+ %31 = phi i32 [ 1, %1 ], [ 0, %17 ]
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 8, i32 0, i64 -1), !dbg !121
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 10, i32 0, i64 -1), !dbg !122
+ ret i32 %31, !dbg !122
+}
+
+; Function Attrs: nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite)
+declare void @llvm.pseudoprobe(i64, i64, i32, i64) #1
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable
+define available_externally dso_local i32 @bar(i32 noundef %0) local_unnamed_addr #3 !dbg !123 !prof !128 {
+ call void @llvm.dbg.value(metadata i32 %0, metadata !127, metadata !DIExpression()), !dbg !129
+ call void @llvm.pseudoprobe(i64 -2012135647395072713, i64 1, i32 0, i64 -1), !dbg !130
+ %2 = add nsw i32 %0, 1, !dbg !131
+ ret i32 %2, !dbg !132
+}
+
+attributes #0 = { nounwind uwtable "disable-tail-calls"="true" "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "use-sample-profile" }
+attributes #1 = { nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite) }
+attributes #2 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+attributes #3 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable "disable-tail-calls"="true" "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "use-sample-profile" }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!2, !7}
+!llvm.module.flags = !{!9, !10, !11, !12, !13, !14, !15, !16, !17}
+!llvm.ident = !{!46, !46}
+!llvm.pseudo_probe_desc = !{!47, !48}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "x", scope: !2, file: !3, line: 2, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C11, file: !3, producer: "clang version 18.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false, debugInfoForProfiling: true, nameTableKind: None)
+!3 = !DIFile(filename: "file1.c", directory: "/home/", checksumkind: CSK_MD5, checksum: "03dfbda098b1285e8c9837f184747483")
+!4 = !{!0}
+!5 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !6)
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = distinct !DICompileUnit(language: DW_LANG_C11, file: !8, producer: "clang version 18.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, debugInfoForProfiling: true, nameTableKind: None)
+!8 = !DIFile(filename: "file2.c", directory: "/home", checksumkind: CSK_MD5, checksum: "bd15f56a5a8604ec94485c3dbf9d0cdd")
+!9 = !{i32 7, !"Dwarf Version", i32 5}
+!10 = !{i32 2, !"Debug Info Version", i32 3}
+!11 = !{i32 1, !"wchar_size", i32 4}
+!12 = !{i32 8, !"PIC Level", i32 2}
+!13 = !{i32 7, !"PIE Level", i32 2}
+!14 = !{i32 7, !"uwtable", i32 2}
+!15 = !{i32 7, !"frame-pointer", i32 2}
+!16 = !{i32 1, !"EnableSplitLTOUnit", i32 0}
+!17 = !{i32 1, !"ProfileSummary", !18}
+!18 = !{!19, !20, !21, !22, !23, !24, !25, !26, !27, !28}
+!19 = !{!"ProfileFormat", !"SampleProfile"}
+!20 = !{!"TotalCount", i64 9258}
+!21 = !{!"MaxCount", i64 2401}
+!22 = !{!"MaxInternalCount", i64 0}
+!23 = !{!"MaxFunctionCount", i64 2401}
+!24 = !{!"NumCounts", i64 18}
+!25 = !{!"NumFunctions", i64 2}
+!26 = !{!"IsPartialProfile", i64 0}
+!27 = !{!"PartialProfileRatio", double 0.000000e+00}
+!28 = !{!"DetailedSummary", !29}
+!29 = !{!30, !31, !32, !33, !34, !35, !36, !37, !38, !39, !40, !41, !42, !43, !44, !45}
+!30 = !{i32 10000, i64 2401, i32 1}
+!31 = !{i32 100000, i64 2401, i32 1}
+!32 = !{i32 200000, i64 2401, i32 1}
+!33 = !{i32 300000, i64 636, i32 2}
+!34 = !{i32 400000, i64 618, i32 4}
+!35 = !{i32 500000, i64 614, i32 8}
+!36 = !{i32 600000, i64 614, i32 8}
+!37 = !{i32 700000, i64 614, i32 8}
+!38 = !{i32 800000, i64 589, i32 10}
+!39 = !{i32 900000, i64 554, i32 11}
+!40 = !{i32 950000, i64 526, i32 12}
+!41 = !{i32 990000, i64 59, i32 16}
+!42 = !{i32 999000, i64 59, i32 16}
+!43 = !{i32 999900, i64 59, i32 16}
+!44 = !{i32 999990, i64 59, i32 16}
+!45 = !{i32 999999, i64 59, i32 16}
+!46 = !{!"clang version 18.0.0"}
+!47 = !{i64 6699318081062747564, i64 563022570642068, !"foo"}
+!48 = !{i64 -2624081020897602054, i64 1126124211449298, !"main"}
+!49 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 11, type: !50, scopeLine: 12, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !52)
+!50 = !DISubroutineType(types: !51)
+!51 = !{!6}
+!52 = !{!53}
+!53 = !DILocalVariable(name: "i", scope: !54, file: !3, line: 13, type: !6)
+!54 = distinct !DILexicalBlock(scope: !49, file: !3, line: 13, column: 3)
+!55 = !{!"function_entry_count", i64 608}
+!56 = !DILocation(line: 13, column: 11, scope: !54)
+!57 = !DILocation(line: 0, scope: !54)
+!58 = !DILocation(line: 13, column: 18, scope: !59)
+!59 = !DILexicalBlockFile(scope: !60, file: !3, discriminator: 0)
+!60 = distinct !DILexicalBlock(scope: !54, file: !3, line: 13, column: 3)
+!61 = !DILocation(line: 13, column: 3, scope: !62)
+!62 = !DILexicalBlockFile(scope: !54, file: !3, discriminator: 2)
+!63 = !DILocation(line: 14, column: 15, scope: !64)
+!64 = distinct !DILexicalBlock(scope: !60, file: !3, line: 13, column: 40)
+!65 = !DILocation(line: 14, column: 18, scope: !64)
+!66 = !{!67, !67, i64 0}
+!67 = !{!"int", !68, i64 0}
+!68 = !{!"omnipotent char", !69, i64 0}
+!69 = !{!"Simple C/C++ TBAA"}
+!70 = !DILocalVariable(name: "i", arg: 1, scope: !71, file: !3, line: 6, type: !6)
+!71 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 6, type: !72, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !74)
+!72 = !DISubroutineType(types: !73)
+!73 = !{!6, !6, !6}
+!74 = !{!70, !75}
+!75 = !DILocalVariable(name: "p", arg: 2, scope: !71, file: !3, line: 6, type: !6)
+!76 = !DILocation(line: 0, scope: !71, inlinedAt: !77)
+!77 = distinct !DILocation(line: 14, column: 11, scope: !78)
+!78 = !DILexicalBlockFile(scope: !64, file: !3, discriminator: 186646631)
+!79 = !DILocation(line: 7, column: 6, scope: !80, inlinedAt: !77)
+!80 = distinct !DILexicalBlock(scope: !71, file: !3, line: 7, column: 6)
+!81 = !DILocation(line: 7, column: 8, scope: !80, inlinedAt: !77)
+!82 = !DILocation(line: 7, column: 6, scope: !71, inlinedAt: !77)
+!83 = !DILocation(line: 0, scope: !80, inlinedAt: !77)
+!84 = !{!"branch_weights", i64 614}
+!85 = !DILocation(line: 9, column: 1, scope: !71, inlinedAt: !77)
+!86 = !DILocation(line: 14, column: 8, scope: !64)
+!87 = !DILocation(line: 15, column: 15, scope: !64)
+!88 = !DILocation(line: 15, column: 11, scope: !89)
+!89 = !DILexicalBlockFile(scope: !64, file: !3, discriminator: 186646639)
+!90 = !{!"branch_weights", i32 614}
+!91 = !DILocation(line: 15, column: 8, scope: !64)
+!92 = !DILocation(line: 16, column: 9, scope: !93)
+!93 = distinct !DILexicalBlock(scope: !64, file: !3, line: 16, column: 9)
+!94 = !DILocation(line: 16, column: 11, scope: !93)
+!95 = !DILocation(line: 16, column: 9, scope: !64)
+!96 = !{!"branch_weights", i32 0, i32 614}
+!97 = !DILocation(line: 18, column: 15, scope: !64)
+!98 = !DILocation(line: 18, column: 18, scope: !64)
+!99 = !DILocation(line: 0, scope: !71, inlinedAt: !100)
+!100 = distinct !DILocation(line: 18, column: 11, scope: !101)
+!101 = !DILexicalBlockFile(scope: !64, file: !3, discriminator: 186646647)
+!102 = !DILocation(line: 7, column: 6, scope: !80, inlinedAt: !100)
+!103 = !DILocation(line: 7, column: 6, scope: !71, inlinedAt: !100)
+!104 = !DILocation(line: 0, scope: !80, inlinedAt: !100)
+!105 = !DILocation(line: 9, column: 1, scope: !71, inlinedAt: !100)
+!106 = !DILocation(line: 18, column: 8, scope: !64)
+!107 = !DILocation(line: 19, column: 15, scope: !64)
+!108 = !DILocation(line: 19, column: 11, scope: !109)
+!109 = !DILexicalBlockFile(scope: !64, file: !3, discriminator: 186646655)
+!110 = !DILocation(line: 19, column: 8, scope: !64)
+!111 = !DILocation(line: 13, column: 36, scope: !59)
+!112 = !DILocation(line: 13, column: 36, scope: !113)
+!113 = !DILexicalBlockFile(scope: !60, file: !3, discriminator: 6)
+!114 = !DILocation(line: 13, column: 20, scope: !115)
+!115 = !DILexicalBlockFile(scope: !60, file: !3, discriminator: 2)
+!116 = !{!"branch_weights", i32 608, i32 614}
+!117 = distinct !{!117, !118, !119, !120}
+!118 = !DILocation(line: 13, column: 3, scope: !54)
+!119 = !DILocation(line: 20, column: 3, scope: !54)
+!120 = !{!"llvm.loop.mustprogress"}
+!121 = !DILocation(line: 0, scope: !49)
+!122 = !DILocation(line: 22, column: 1, scope: !49)
+!123 = distinct !DISubprogram(name: "bar", scope: !8, file: !8, line: 1, type: !124, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !126)
+!124 = !DISubroutineType(types: !125)
+!125 = !{!6, !6}
+!126 = !{!127}
+!127 = !DILocalVariable(name: "x", arg: 1, scope: !123, file: !8, line: 1, type: !6)
+!128 = !{!"function_entry_count", i64 2401}
+!129 = !DILocation(line: 0, scope: !123)
+!130 = !DILocation(line: 5, column: 10, scope: !123)
+!131 = !DILocation(line: 5, column: 12, scope: !123)
+!132 = !DILocation(line: 5, column: 3, scope: !123)
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I don't have commit access, so I can't assign reviewers, but tagging @xur-llvm @wlei-llvm. |
david-xl
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Mar 21, 2024
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This should help AutoFDO too. We didn't turn it on because we didn't test it throughly for AutoFDO. Also note that the matching algorithm may not be a no-op for perfectly matched profile. Since we don't have checksum for AutoFDO, we can only apply matching to all functions, which may have undesired side effects for good/matched profiles. |
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FWIW, there is a TODO of LTO time matching for AutoFDO path, see: https://github.com/llvm/llvm-project/blob/main/llvm/lib/Transforms/IPO/SampleProfile.cpp#L2239, it doesn't extract the non-callsite line-location anchor, so the regular instruction still uses the old mapping which may lead to inaccurate block count. At that time, we only compute the staleness stats for AutoFDO path, so I didn't add the support to save some build-time. |
wlei-llvm
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Mar 22, 2024
llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching.ll
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Yes, I'm aware of this TODO and I plan to work on it afterwards. Properly matching just callsite line-locations helps a lot on itself too: it affects the inlining behaviour of the sample profile loader. If |
wlei-llvm
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LGTM, thanks. Just a friendly heads-up, there is a bug related to callee profile matches, and I'm working on the fix(see #85715), it works for checksum(probe-based) profile. But as Wenlei pointed out, there is no checksum thing for AutoFDO, so even the user function code is not changed, i,e. the profile is not stale, all functions(after the fix, all callees) will run the "stale" profile matching, and it might not be a no-op(e.g. cold or optimized-out callsite might not show in the profile, hopefully cold callsite are insignificant, but I'm not sure) and might cause negative effect to this perfectly matched case.
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Thanks for the review! I rebased the changes (there were some merge conflicts) and squashed them into one commit. I don't have write access to LLVM (and in the light of what happened last week I'm not sure if we all want to have even more people with write access to critical infrastructure...), so I'd like to ask someone to merge the PR. |
Currently -salvage-stale-profile is a no-op if the profile is not probe-based. We observed that it can help for regular, non-probe- based profiles too: some of our internal benchmarks show 0.2-0.3% QPS improvement. There seems to be no good reason to limit this flag to only work for probe-based profiles.
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Currently -salvage-stale-profile is a no-op if the profile is not probe-based. We observed that it can help for regular, non-probe- based profiles too: some of our internal benchmarks show 0.2-0.3% QPS improvement.
There seems to be no good reason to limit this flag to only work for probe-based profiles.