Committee-aware attestation packing (#14245)

* initial algorithm

* ready for review

* feature flag

* typo

* review

* comment fix

* fix TestProposer_sort_DifferentCommittees

* flag usage

beacon-chain/rpc/prysm/v1alpha1/validator/proposer_attestations.go

@@ -11,6 +11,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v5/config/features"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
 	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
@@ -112,18 +113,12 @@ func (vs *Server) packAttestations(ctx context.Context, latestState state.Beacon
 	if err != nil {
 		return nil, err
 	}
-	sorted, err := deduped.sortByProfitability()
+	sorted, err := deduped.sort()
 	if err != nil {
 		return nil, err
 	}
 	atts = sorted.limitToMaxAttestations()
-
-	atts, err = vs.filterAttestationBySignature(ctx, atts, latestState)
-	if err != nil {
-		return nil, err
-	}
-
-	return atts, nil
+	return vs.filterAttestationBySignature(ctx, atts, latestState)
 }
 
 // filter separates attestation list into two groups: valid and invalid attestations.
@@ -143,14 +138,6 @@ func (a proposerAtts) filter(ctx context.Context, st state.BeaconState) (propose
 	return validAtts, invalidAtts
 }
 
-// sortByProfitability orders attestations by highest slot and by highest aggregation bit count.
-func (a proposerAtts) sortByProfitability() (proposerAtts, error) {
-	if len(a) < 2 {
-		return a, nil
-	}
-	return a.sortByProfitabilityUsingMaxCover()
-}
-
 // sortByProfitabilityUsingMaxCover orders attestations by highest slot and by highest aggregation bit count.
 // Duplicate bits are counted only once, using max-cover algorithm.
 func (a proposerAtts) sortByProfitabilityUsingMaxCover() (proposerAtts, error) {
@@ -218,6 +205,143 @@ func (a proposerAtts) sortByProfitabilityUsingMaxCover() (proposerAtts, error) {
 	return sortedAtts, nil
 }
 
+// sort attestations as follows:
+//
+//   - all attestations selected by max-cover are taken, leftover attestations are discarded
+//     (with current parameters all bits of a leftover attestation are already covered by selected attestations)
+//   - selected attestations are ordered by slot, with higher slot coming first
+//   - within a slot, all top attestations (one per committee) are ordered before any second-best attestations, second-best before third-best etc.
+//   - within top/second-best/etc. attestations (one per committee), attestations are ordered by bit count, with higher bit count coming first
+func (a proposerAtts) sort() (proposerAtts, error) {
+	if len(a) < 2 {
+		return a, nil
+	}
+
+	if features.Get().EnableCommitteeAwarePacking {
+		return a.sortBySlotAndCommittee()
+	}
+	return a.sortByProfitabilityUsingMaxCover()
+}
+
+// Separate attestations by slot, as slot number takes higher precedence when sorting.
+// Also separate by committee index because maxcover will prefer attestations for the same
+// committee with disjoint bits over attestations for different committees with overlapping
+// bits, even though same bits for different committees are separate votes.
+func (a proposerAtts) sortBySlotAndCommittee() (proposerAtts, error) {
+	type slotAtts struct {
+		candidates map[primitives.CommitteeIndex]proposerAtts
+		selected   map[primitives.CommitteeIndex]proposerAtts
+		leftover   map[primitives.CommitteeIndex]proposerAtts
+	}
+
+	var slots []primitives.Slot
+	attsBySlot := map[primitives.Slot]*slotAtts{}
+	for _, att := range a {
+		slot := att.GetData().Slot
+		ci := att.GetData().CommitteeIndex
+		if _, ok := attsBySlot[slot]; !ok {
+			attsBySlot[slot] = &slotAtts{}
+			attsBySlot[slot].candidates = make(map[primitives.CommitteeIndex]proposerAtts)
+			slots = append(slots, slot)
+		}
+		attsBySlot[slot].candidates[ci] = append(attsBySlot[slot].candidates[ci], att)
+	}
+
+	var err error
+	for _, sa := range attsBySlot {
+		sa.selected = make(map[primitives.CommitteeIndex]proposerAtts)
+		sa.leftover = make(map[primitives.CommitteeIndex]proposerAtts)
+		for ci, committeeAtts := range sa.candidates {
+			sa.selected[ci], err = committeeAtts.sortByProfitabilityUsingMaxCover_committeeAwarePacking()
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	var sortedAtts proposerAtts
+	sort.Slice(slots, func(i, j int) bool {
+		return slots[i] > slots[j]
+	})
+	for _, slot := range slots {
+		sortedAtts = append(sortedAtts, sortSlotAttestations(attsBySlot[slot].selected)...)
+	}
+	for _, slot := range slots {
+		sortedAtts = append(sortedAtts, sortSlotAttestations(attsBySlot[slot].leftover)...)
+	}
+
+	return sortedAtts, nil
+}
+
+// sortByProfitabilityUsingMaxCover orders attestations by highest aggregation bit count.
+// Duplicate bits are counted only once, using max-cover algorithm.
+func (a proposerAtts) sortByProfitabilityUsingMaxCover_committeeAwarePacking() (proposerAtts, error) {
+	if len(a) < 2 {
+		return a, nil
+	}
+	candidates := make([]*bitfield.Bitlist64, len(a))
+	for i := 0; i < len(a); i++ {
+		var err error
+		candidates[i], err = a[i].GetAggregationBits().ToBitlist64()
+		if err != nil {
+			return nil, err
+		}
+	}
+	// Add selected candidates on top, those that are not selected - append at bottom.
+	selectedKeys, _, err := aggregation.MaxCover(candidates, len(candidates), true /* allowOverlaps */)
+	if err != nil {
+		log.WithError(err).Debug("MaxCover aggregation failed")
+		return a, nil
+	}
+
+	// Pick selected attestations first, leftover attestations will be appended at the end.
+	// Both lists will be sorted by number of bits set.
+	selected := make(proposerAtts, selectedKeys.Count())
+	for i, key := range selectedKeys.BitIndices() {
+		selected[i] = a[key]
+	}
+	sort.Slice(selected, func(i, j int) bool {
+		return selected[i].GetAggregationBits().Count() > selected[j].GetAggregationBits().Count()
+	})
+	return selected, nil
+}
+
+// sortSlotAttestations assumes each proposerAtts value in the map is ordered by profitability.
+// The function takes the first attestation from each value, orders these attestations by bit count
+// and places them at the start of the resulting slice. It then takes the second attestation for each value,
+// orders these attestations by bit count and appends them to the end.
+// It continues this pattern until all attestations are processed.
+func sortSlotAttestations(slotAtts map[primitives.CommitteeIndex]proposerAtts) proposerAtts {
+	attCount := 0
+	for _, committeeAtts := range slotAtts {
+		attCount += len(committeeAtts)
+	}
+
+	sorted := make([]ethpb.Att, 0, attCount)
+
+	processedCount := 0
+	index := 0
+	for processedCount < attCount {
+		var atts []ethpb.Att
+
+		for _, committeeAtts := range slotAtts {
+			if len(committeeAtts) > index {
+				atts = append(atts, committeeAtts[index])
+			}
+		}
+
+		sort.Slice(atts, func(i, j int) bool {
+			return atts[i].GetAggregationBits().Count() > atts[j].GetAggregationBits().Count()
+		})
+		sorted = append(sorted, atts...)
+
+		processedCount += len(atts)
+		index++
+	}
+
+	return sorted
+}
+
 // limitToMaxAttestations limits attestations to maximum attestations per block.
 func (a proposerAtts) limitToMaxAttestations() proposerAtts {
 	if len(a) == 0 {

beacon-chain/rpc/prysm/v1alpha1/validator/proposer_attestations_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/prysmaticlabs/go-bitfield"
 	chainMock "github.com/prysmaticlabs/prysm/v5/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/operations/attestations"
+	"github.com/prysmaticlabs/prysm/v5/config/features"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v5/crypto/bls/blst"
@@ -19,31 +20,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
 )
 
-func TestProposer_ProposerAtts_sortByProfitability(t *testing.T) {
-	atts := proposerAtts([]ethpb.Att{
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 4}, AggregationBits: bitfield.Bitlist{0b11100000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 1}, AggregationBits: bitfield.Bitlist{0b11000000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 2}, AggregationBits: bitfield.Bitlist{0b11100000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 4}, AggregationBits: bitfield.Bitlist{0b11110000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 1}, AggregationBits: bitfield.Bitlist{0b11100000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 3}, AggregationBits: bitfield.Bitlist{0b11000000}}),
-	})
-	want := proposerAtts([]ethpb.Att{
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 4}, AggregationBits: bitfield.Bitlist{0b11110000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 4}, AggregationBits: bitfield.Bitlist{0b11100000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 3}, AggregationBits: bitfield.Bitlist{0b11000000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 2}, AggregationBits: bitfield.Bitlist{0b11100000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 1}, AggregationBits: bitfield.Bitlist{0b11100000}}),
-		util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 1}, AggregationBits: bitfield.Bitlist{0b11000000}}),
-	})
-	atts, err := atts.sortByProfitability()
-	if err != nil {
-		t.Error(err)
-	}
-	require.DeepEqual(t, want, atts)
-}
-
-func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
+func TestProposer_ProposerAtts_sort(t *testing.T) {
 	type testData struct {
 		slot primitives.Slot
 		bits bitfield.Bitlist
@@ -60,7 +37,7 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 	t.Run("no atts", func(t *testing.T) {
 		atts := getAtts([]testData{})
 		want := getAtts([]testData{})
-		atts, err := atts.sortByProfitability()
+		atts, err := atts.sort()
 		if err != nil {
 			t.Error(err)
 		}
@@ -74,7 +51,7 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 		want := getAtts([]testData{
 			{4, bitfield.Bitlist{0b11100000, 0b1}},
 		})
-		atts, err := atts.sortByProfitability()
+		atts, err := atts.sort()
 		if err != nil {
 			t.Error(err)
 		}
@@ -90,7 +67,7 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 			{4, bitfield.Bitlist{0b11100000, 0b1}},
 			{1, bitfield.Bitlist{0b11000000, 0b1}},
 		})
-		atts, err := atts.sortByProfitability()
+		atts, err := atts.sort()
 		if err != nil {
 			t.Error(err)
 		}
@@ -108,7 +85,7 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 			{4, bitfield.Bitlist{0b11100000, 0b1}},
 			{1, bitfield.Bitlist{0b11000000, 0b1}},
 		})
-		atts, err := atts.sortByProfitability()
+		atts, err := atts.sort()
 		if err != nil {
 			t.Error(err)
 		}
@@ -129,7 +106,7 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 				{1, bitfield.Bitlist{0b00001100, 0b1}},
 				{1, bitfield.Bitlist{0b11001000, 0b1}},
 			})
-			atts, err := atts.sortByProfitability()
+			atts, err := atts.sort()
 			if err != nil {
 				t.Error(err)
 			}
@@ -154,14 +131,14 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 			{1, bitfield.Bitlist{0b11100000, 0b1}},
 			{1, bitfield.Bitlist{0b11000000, 0b1}},
 		})
-		atts, err := atts.sortByProfitability()
+		atts, err := atts.sort()
 		if err != nil {
 			t.Error(err)
 		}
 		require.DeepEqual(t, want, atts)
 	})
 
-	t.Run("selected and non selected atts sorted by bit count", func(t *testing.T) {
+	t.Run("follows max-cover", func(t *testing.T) {
 		// Items at slot 4, must be first split into two lists by max-cover, with
 		// 0b10000011 scoring higher (as it provides more info in addition to already selected
 		// attestations) than 0b11100001 (despite naive bit count suggesting otherwise). Then,
@@ -186,7 +163,7 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 			{1, bitfield.Bitlist{0b11100000, 0b1}},
 			{1, bitfield.Bitlist{0b11000000, 0b1}},
 		})
-		atts, err := atts.sortByProfitability()
+		atts, err := atts.sort()
 		if err != nil {
 			t.Error(err)
 		}
@@ -194,6 +171,241 @@ func TestProposer_ProposerAtts_sortByProfitabilityUsingMaxCover(t *testing.T) {
 	})
 }
 
+func TestProposer_ProposerAtts_committeeAwareSort(t *testing.T) {
+	type testData struct {
+		slot primitives.Slot
+		bits bitfield.Bitlist
+	}
+	getAtts := func(data []testData) proposerAtts {
+		var atts proposerAtts
+		for _, att := range data {
+			atts = append(atts, util.HydrateAttestation(&ethpb.Attestation{
+				Data: &ethpb.AttestationData{Slot: att.slot}, AggregationBits: att.bits}))
+		}
+		return atts
+	}
+
+	t.Run("no atts", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		atts := getAtts([]testData{})
+		want := getAtts([]testData{})
+		atts, err := atts.sort()
+		if err != nil {
+			t.Error(err)
+		}
+		require.DeepEqual(t, want, atts)
+	})
+
+	t.Run("single att", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		atts := getAtts([]testData{
+			{4, bitfield.Bitlist{0b11100000, 0b1}},
+		})
+		want := getAtts([]testData{
+			{4, bitfield.Bitlist{0b11100000, 0b1}},
+		})
+		atts, err := atts.sort()
+		if err != nil {
+			t.Error(err)
+		}
+		require.DeepEqual(t, want, atts)
+	})
+
+	t.Run("single att per slot", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		atts := getAtts([]testData{
+			{1, bitfield.Bitlist{0b11000000, 0b1}},
+			{4, bitfield.Bitlist{0b11100000, 0b1}},
+		})
+		want := getAtts([]testData{
+			{4, bitfield.Bitlist{0b11100000, 0b1}},
+			{1, bitfield.Bitlist{0b11000000, 0b1}},
+		})
+		atts, err := atts.sort()
+		if err != nil {
+			t.Error(err)
+		}
+		require.DeepEqual(t, want, atts)
+	})
+
+	t.Run("two atts on one of the slots", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		atts := getAtts([]testData{
+			{1, bitfield.Bitlist{0b11000000, 0b1}},
+			{4, bitfield.Bitlist{0b11100000, 0b1}},
+			{4, bitfield.Bitlist{0b11110000, 0b1}},
+		})
+		want := getAtts([]testData{
+			{4, bitfield.Bitlist{0b11110000, 0b1}},
+			{1, bitfield.Bitlist{0b11000000, 0b1}},
+		})
+		atts, err := atts.sort()
+		if err != nil {
+			t.Error(err)
+		}
+		require.DeepEqual(t, want, atts)
+	})
+
+	t.Run("compare to native sort", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		// The max-cover based approach will select 0b00001100 instead, despite lower bit count
+		// (since it has two new/unknown bits).
+		t.Run("max-cover", func(t *testing.T) {
+			atts := getAtts([]testData{
+				{1, bitfield.Bitlist{0b11000011, 0b1}},
+				{1, bitfield.Bitlist{0b11001000, 0b1}},
+				{1, bitfield.Bitlist{0b00001100, 0b1}},
+			})
+			want := getAtts([]testData{
+				{1, bitfield.Bitlist{0b11000011, 0b1}},
+				{1, bitfield.Bitlist{0b00001100, 0b1}},
+			})
+			atts, err := atts.sort()
+			if err != nil {
+				t.Error(err)
+			}
+			require.DeepEqual(t, want, atts)
+		})
+	})
+
+	t.Run("multiple slots", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		atts := getAtts([]testData{
+			{2, bitfield.Bitlist{0b11100000, 0b1}},
+			{4, bitfield.Bitlist{0b11100000, 0b1}},
+			{1, bitfield.Bitlist{0b11000000, 0b1}},
+			{4, bitfield.Bitlist{0b11110000, 0b1}},
+			{1, bitfield.Bitlist{0b11100000, 0b1}},
+			{3, bitfield.Bitlist{0b11000000, 0b1}},
+		})
+		want := getAtts([]testData{
+			{4, bitfield.Bitlist{0b11110000, 0b1}},
+			{3, bitfield.Bitlist{0b11000000, 0b1}},
+			{2, bitfield.Bitlist{0b11100000, 0b1}},
+			{1, bitfield.Bitlist{0b11100000, 0b1}},
+		})
+		atts, err := atts.sort()
+		if err != nil {
+			t.Error(err)
+		}
+		require.DeepEqual(t, want, atts)
+	})
+
+	t.Run("follows max-cover", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		// Items at slot 4 must be first split into two lists by max-cover, with
+		// 0b10000011 being selected and 0b11100001 being leftover (despite naive bit count suggesting otherwise).
+		atts := getAtts([]testData{
+			{4, bitfield.Bitlist{0b00000001, 0b1}},
+			{4, bitfield.Bitlist{0b11100001, 0b1}},
+			{1, bitfield.Bitlist{0b11000000, 0b1}},
+			{2, bitfield.Bitlist{0b11100000, 0b1}},
+			{4, bitfield.Bitlist{0b10000011, 0b1}},
+			{4, bitfield.Bitlist{0b11111000, 0b1}},
+			{1, bitfield.Bitlist{0b11100000, 0b1}},
+			{3, bitfield.Bitlist{0b11000000, 0b1}},
+		})
+		want := getAtts([]testData{
+			{4, bitfield.Bitlist{0b11111000, 0b1}},
+			{4, bitfield.Bitlist{0b10000011, 0b1}},
+			{3, bitfield.Bitlist{0b11000000, 0b1}},
+			{2, bitfield.Bitlist{0b11100000, 0b1}},
+			{1, bitfield.Bitlist{0b11100000, 0b1}},
+		})
+		atts, err := atts.sort()
+		if err != nil {
+			t.Error(err)
+		}
+		require.DeepEqual(t, want, atts)
+	})
+}
+
+func TestProposer_sort_DifferentCommittees(t *testing.T) {
+	t.Run("one att per committee", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		c1_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11111000, 0b1}, Data: &ethpb.AttestationData{CommitteeIndex: 1}})
+		c2_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11100000, 0b1}, Data: &ethpb.AttestationData{CommitteeIndex: 2}})
+		atts := proposerAtts{c1_a1, c2_a1}
+		atts, err := atts.sort()
+		require.NoError(t, err)
+		want := proposerAtts{c1_a1, c2_a1}
+		assert.DeepEqual(t, want, atts)
+	})
+	t.Run("multiple atts per committee", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		c1_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11111100, 0b1}, Data: &ethpb.AttestationData{CommitteeIndex: 1}})
+		c1_a2 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b10000010, 0b1}, Data: &ethpb.AttestationData{CommitteeIndex: 1}})
+		c2_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11110000, 0b1}, Data: &ethpb.AttestationData{CommitteeIndex: 2}})
+		c2_a2 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11100000, 0b1}, Data: &ethpb.AttestationData{CommitteeIndex: 2}})
+		atts := proposerAtts{c1_a1, c1_a2, c2_a1, c2_a2}
+		atts, err := atts.sort()
+		require.NoError(t, err)
+
+		want := proposerAtts{c1_a1, c2_a1, c1_a2}
+		assert.DeepEqual(t, want, atts)
+	})
+	t.Run("multiple atts per committee, multiple slots", func(t *testing.T) {
+		feat := features.Get()
+		feat.EnableCommitteeAwarePacking = true
+		reset := features.InitWithReset(feat)
+		defer reset()
+
+		s2_c1_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11111100, 0b1}, Data: &ethpb.AttestationData{Slot: 2, CommitteeIndex: 1}})
+		s2_c1_a2 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b10000010, 0b1}, Data: &ethpb.AttestationData{Slot: 2, CommitteeIndex: 1}})
+		s2_c2_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11110000, 0b1}, Data: &ethpb.AttestationData{Slot: 2, CommitteeIndex: 2}})
+		s2_c2_a2 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11000000, 0b1}, Data: &ethpb.AttestationData{Slot: 2, CommitteeIndex: 2}})
+		s1_c1_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11111100, 0b1}, Data: &ethpb.AttestationData{Slot: 1, CommitteeIndex: 1}})
+		s1_c1_a2 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b10000010, 0b1}, Data: &ethpb.AttestationData{Slot: 1, CommitteeIndex: 1}})
+		s1_c2_a1 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11110000, 0b1}, Data: &ethpb.AttestationData{Slot: 1, CommitteeIndex: 2}})
+		s1_c2_a2 := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.Bitlist{0b11000000, 0b1}, Data: &ethpb.AttestationData{Slot: 1, CommitteeIndex: 2}})
+
+		// Arrange in some random order
+		atts := proposerAtts{s1_c1_a1, s2_c1_a2, s1_c2_a2, s2_c2_a2, s1_c2_a1, s2_c2_a1, s1_c1_a2, s2_c1_a1}
+
+		atts, err := atts.sort()
+		require.NoError(t, err)
+
+		want := proposerAtts{s2_c1_a1, s2_c2_a1, s2_c1_a2, s1_c1_a1, s1_c2_a1, s1_c1_a2}
+		assert.DeepEqual(t, want, atts)
+	})
+}
+
 func TestProposer_ProposerAtts_dedup(t *testing.T) {
 	data1 := util.HydrateAttestationData(&ethpb.AttestationData{
 		Slot: 4,

beacon-chain/rpc/prysm/v1alpha1/validator/proposer_utils_bench_test.go

@@ -49,7 +49,7 @@ func BenchmarkProposerAtts_sortByProfitability(b *testing.B) {
 		for i, att := range atts {
 			attsCopy[i] = att.(*ethpb.Attestation).Copy()
 		}
-		_, err := attsCopy.sortByProfitability()
+		_, err := attsCopy.sort()
 		require.NoError(b, err, "Could not sort attestations by profitability")
 	}
 

config/features/config.go

@@ -48,6 +48,7 @@ type Flags struct {
 	EnableDoppelGanger                  bool // EnableDoppelGanger enables doppelganger protection on startup for the validator.
 	EnableHistoricalSpaceRepresentation bool // EnableHistoricalSpaceRepresentation enables the saving of registry validators in separate buckets to save space
 	EnableBeaconRESTApi                 bool // EnableBeaconRESTApi enables experimental usage of the beacon REST API by the validator when querying a beacon node
+	EnableCommitteeAwarePacking         bool // EnableCommitteeAwarePacking TODO
 	// Logging related toggles.
 	DisableGRPCConnectionLogs bool // Disables logging when a new grpc client has connected.
 	EnableFullSSZDataLogging  bool // Enables logging for full ssz data on rejected gossip messages
@@ -254,6 +255,10 @@ func ConfigureBeaconChain(ctx *cli.Context) error {
 		logEnabled(EnableQUIC)
 		cfg.EnableQUIC = true
 	}
+	if ctx.IsSet(EnableCommitteeAwarePacking.Name) {
+		logEnabled(EnableCommitteeAwarePacking)
+		cfg.EnableCommitteeAwarePacking = true
+	}
 
 	cfg.AggregateIntervals = [3]time.Duration{aggregateFirstInterval.Value, aggregateSecondInterval.Value, aggregateThirdInterval.Value}
 	Init(cfg)

config/features/flags.go

@@ -166,6 +166,10 @@ var (
 		Name:  "enable-quic",
 		Usage: "Enables connection using the QUIC protocol for peers which support it.",
 	}
+	EnableCommitteeAwarePacking = &cli.BoolFlag{
+		Name:  "enable-committee-aware-packing",
+		Usage: "Changes the attestation packing algorithm to one that is aware of attesting committees.",
+	}
 )
 
 // devModeFlags holds list of flags that are set when development mode is on.
@@ -223,6 +227,7 @@ var BeaconChainFlags = append(deprecatedBeaconFlags, append(deprecatedFlags, []c
 	EnableLightClient,
 	BlobSaveFsync,
 	EnableQUIC,
+	EnableCommitteeAwarePacking,
 }...)...)
 
 // E2EBeaconChainFlags contains a list of the beacon chain feature flags to be tested in E2E.

proto/prysm/v1alpha1/attestation/aggregation/maxcover_test.go

@@ -663,6 +663,18 @@ func TestMaxCover_MaxCover(t *testing.T) {
 			}},
 			wantedErr: "empty bitlists: invalid max_cover problem",
 		},
+		{
+			name: "doesn't select bitlist which is a subset of another bitlist",
+			args: args{k: 3, allowOverlaps: true, candidates: []*bitfield.Bitlist64{
+				bitfield.NewBitlist64From([]uint64{0b00011100}),
+				bitfield.NewBitlist64From([]uint64{0b00011110}),
+				bitfield.NewBitlist64From([]uint64{0b00000001}),
+			}},
+			want: &BitSetAggregation{
+				Coverage: bitfield.NewBitlist64From([]uint64{0b00011111}),
+				Keys:     []int{1, 2},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {