shrink batches when over 80% of the space is wasted (backport #23066) (#23189)

* shrink batches when over 80% of the space is wasted (#23066)

* shrink batches when over 80% of the space is wasted

(cherry picked from commit 83d31c9e65)

# Conflicts:
#	core/benches/sigverify_stage.rs
#	core/src/sigverify_stage.rs
#	perf/src/sigverify.rs

* fixup!

Co-authored-by: anatoly yakovenko <anatoly@solana.com>

perf/benches/shrink.rs

@@ -0,0 +1,86 @@
+#![allow(clippy::integer_arithmetic)]
+#![feature(test)]
+
+extern crate test;
+
+use {
+    rand::prelude::*,
+    solana_perf::{
+        packet::{to_packet_batches, PacketBatch, PACKETS_PER_BATCH},
+        sigverify,
+    },
+    test::Bencher,
+};
+
+const NUM_PACKETS: usize = 1024 * 4;
+
+fn test_packet_with_size(size: usize, rng: &mut ThreadRng) -> Vec<u8> {
+    // subtract 8 bytes because the length will get serialized as well
+    (0..size.checked_sub(8).unwrap())
+        .map(|_| rng.gen())
+        .collect()
+}
+
+fn do_bench_shrink_packets(bencher: &mut Bencher, mut batches: Vec<PacketBatch>) {
+    // verify packets
+    bencher.iter(|| {
+        let _ans = sigverify::shrink_batches(&mut batches);
+        batches.iter_mut().for_each(|b| {
+            b.packets
+                .iter_mut()
+                .for_each(|p| p.meta.set_discard(thread_rng().gen()))
+        });
+    });
+}
+
+#[bench]
+#[ignore]
+fn bench_shrink_diff_small_packets(bencher: &mut Bencher) {
+    let mut rng = rand::thread_rng();
+
+    let batches = to_packet_batches(
+        &(0..NUM_PACKETS)
+            .map(|_| test_packet_with_size(128, &mut rng))
+            .collect::<Vec<_>>(),
+        PACKETS_PER_BATCH,
+    );
+
+    do_bench_shrink_packets(bencher, batches);
+}
+
+#[bench]
+#[ignore]
+fn bench_shrink_diff_big_packets(bencher: &mut Bencher) {
+    let mut rng = rand::thread_rng();
+
+    let batches = to_packet_batches(
+        &(0..NUM_PACKETS)
+            .map(|_| test_packet_with_size(1024, &mut rng))
+            .collect::<Vec<_>>(),
+        PACKETS_PER_BATCH,
+    );
+
+    do_bench_shrink_packets(bencher, batches);
+}
+
+#[bench]
+#[ignore]
+fn bench_shrink_count_packets(bencher: &mut Bencher) {
+    let mut rng = rand::thread_rng();
+
+    let mut batches = to_packet_batches(
+        &(0..NUM_PACKETS)
+            .map(|_| test_packet_with_size(128, &mut rng))
+            .collect::<Vec<_>>(),
+        PACKETS_PER_BATCH,
+    );
+    batches.iter_mut().for_each(|b| {
+        b.packets
+            .iter_mut()
+            .for_each(|p| p.meta.set_discard(thread_rng().gen()))
+    });
+
+    bencher.iter(|| {
+        let _ = sigverify::count_valid_packets(&batches);
+    });
+}