perf test: Add false_sharing workload exhibiting cross-CPU false sharing

Add a 'perf test -w false_sharing' workload that hammers one shared
struct from several CPUs, shaped as a TCP connection: a read-mostly
identity (five-tuple) shares a cacheline with per-packet rx counters
(the false-sharing line), a second line has packet-path private tx and
congestion control counters, and a third the connection config.

The packet path runs in the main thread and up to four lookup threads
sum the five-tuple and pull the config, reading one volatile shared
instance directly so the accesses are PC-relative and resolvable by the
data type profiler.

Data type profiling of the workload with cacheline info:

  $ perf mem record -- perf test -r5 -w false_sharing
  [ perf record: Woken up 19 times to write data ]
  [ perf record: Captured and wrote 5.612 MB perf.data (72454 samples) ]
  $ perf report -s type,typecln -H --group --stdio
  # Total Lost Samples: 0
  #
  # Samples: 72K of events 'cpu/mem-loads,ldlat=30/P, cpu/mem-stores/P'
  # Event count (approx.): 1261814616
  #
  #            Overhead  Data Type / Data Type Cacheline
  # ...................  ...............................
  #
      88.99%  35.88%     struct net_conn
         56.43%  17.50%     struct net_conn: cache-line 0
         32.55%   0.00%     struct net_conn: cache-line 2
          0.01%  18.38%     struct net_conn: cache-line 1
      10.08%  63.03%     (unknown)
         10.08%  63.03%     (unknown): cache-line 0
       0.82%   0.13%     int
          0.82%   0.13%     int: cache-line 0
       0.01%   0.02%     struct folio
          0.01%   0.02%     struct folio: cache-line 0
       0.01%   0.03%     Elf64_Addr
          0.01%   0.03%     Elf64_Addr: cache-line 0
       0.01%   0.03%     struct sched_entity
          0.01%   0.03%     struct sched_entity: cache-line 1
          0.00%   0.00%     struct sched_entity: cache-line 4
          0.00%   0.00%     struct sched_entity: cache-line 2
          0.00%   0.00%     struct sched_entity: cache-line 3
          0.00%   0.00%     struct sched_entity: cache-line 0
       0.01%   0.00%     struct task_group
          0.01%   0.00%     struct task_group: cache-line 4
          0.00%   0.00%     struct task_group: cache-line 5
       0.00%   0.00%     struct css_rstat_cpu
          0.00%   0.00%     struct css_rstat_cpu: cache-line 0
  $ perf report -s type,typecln,typeoff -H --group --stdio
  # Total Lost Samples: 0
  #
  # Samples: 72K of events 'cpu/mem-loads,ldlat=30/P, cpu/mem-stores/P'
  # Event count (approx.): 1261814616
  #
  #               Overhead  Data Type / Data Type Cacheline / Data Type Offset
  # ......................  ..................................................
  #
      88.99%  35.88%        struct net_conn
         56.43%  17.50%        struct net_conn: cache-line 0
             9.81%   0.00%        struct net_conn +0xa (dport)
             9.54%   0.00%        struct net_conn +0x8 (sport)
             9.53%   0.00%        struct net_conn +0xc (state)
             9.48%   0.00%        struct net_conn +0xd (protocol)
             9.27%   0.00%        struct net_conn +0x4 (daddr)
             8.79%   0.00%        struct net_conn +0 (saddr)
             0.00%  12.08%        struct net_conn +0x10 (bytes_rx)
             0.00%   1.71%        struct net_conn +0x18 (packets_rx)
             0.00%   2.80%        struct net_conn +0x20 (rx_queue)
             0.00%   0.91%        struct net_conn +0x3c (last_ack)
         32.55%   0.00%        struct net_conn: cache-line 2
             5.70%   0.00%        struct net_conn +0x83 (rcv_wscale)
             5.46%   0.00%        struct net_conn +0x84 (keepalive_int)
             5.43%   0.00%        struct net_conn +0x82 (snd_wscale)
             5.39%   0.00%        struct net_conn +0x80 (mss)
             5.34%   0.00%        struct net_conn +0x88 (mark)
             5.23%   0.00%        struct net_conn +0x8c (priority)
          0.01%  18.38%        struct net_conn: cache-line 1
             0.01%   0.05%        struct net_conn +0x5c (retrans)
             0.00%   4.83%        struct net_conn +0x40 (bytes_tx)
             0.00%  10.63%        struct net_conn +0x48 (packets_tx)
             0.00%   1.54%        struct net_conn +0x58 (rtt_us)
             0.00%   1.07%        struct net_conn +0x50 (cwnd)
             0.00%   0.25%        struct net_conn +0x54 (ssthresh)
      10.08%  63.03%        (unknown)
         10.08%  63.03%        (unknown): cache-line 0
            10.08%  63.03%        (unknown)
       0.82%   0.13%        int
          0.82%   0.13%        int: cache-line 0
             0.82%   0.13%        int +0 (no field)
       0.01%   0.02%        struct folio
          0.01%   0.02%        struct folio: cache-line 0
             0.01%   0.00%        struct folio +0 (flags.f)
             0.00%   0.01%        struct folio +0x34 (_refcount.counter)
             0.00%   0.00%        struct folio +0x18 (mapping)

Assisted-by: LLM
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/tools/perf/tests/shell/data_type_profiling.sh b/tools/perf/tests/shell/data_type_profiling.sh
index a916c410274a..57203e0e5f85 100755
--- a/tools/perf/tests/shell/data_type_profiling.sh
+++ b/tools/perf/tests/shell/data_type_profiling.sh
@@ -8,8 +8,8 @@ set -e
 # data type profiling manifestation
 
 # Values in testtypes and testprogs should match
-testtypes=("# data-type: struct Buf" "# data-type: struct buf")
-testprogs=("perf test -w code_with_type" "perf test -w datasym")
+testtypes=("# data-type: struct Buf" "# data-type: struct buf" "# data-type: struct net_conn")
+testprogs=("perf test -w code_with_type" "perf test -w datasym" "perf test -w false_sharing")
 
 err=0
 perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
@@ -59,6 +59,9 @@ test_basic_annotate() {
 
     "xC")
     index=1 ;;
+
+    "xFS")
+    index=2 ;;
   esac
 
   # Under 'set -e' a bare failing command aborts the script through the EXIT
@@ -114,6 +117,8 @@ test_basic_annotate Basic Rust
 test_basic_annotate Pipe Rust
 test_basic_annotate Basic C
 test_basic_annotate Pipe C
+test_basic_annotate Basic FS
+test_basic_annotate Pipe FS
 
 cleanup
 exit $err