tests: syscall_test_runner should not run tests in parallel

bazel runs a few instances of syscall_test_runner in parallel
and then syscall_test_runner runs test cases in parallel. It might
be a reason why we see that test hosts are overloaded and sandboxes
start slowly. It should be better to control how many tests are
running in parallel from one place, so let's try to disable this
feature in syscall_test_runner.

PiperOrigin-RevId: 264434674

test/syscalls/BUILD

@@ -27,6 +27,7 @@ syscall_test(
 
 syscall_test(
     size = "medium",
+    shard_count = 5,
     test = "//test/syscalls/linux:alarm_test",
 )
 
@@ -185,6 +186,7 @@ syscall_test(
 
 syscall_test(
     size = "medium",
+    shard_count = 5,
     test = "//test/syscalls/linux:itimer_test",
 )
 
@@ -296,8 +298,6 @@ syscall_test(test = "//test/syscalls/linux:priority_test")
 
 syscall_test(
     size = "medium",
-    # We don't want our proc changing out from under us.
-    parallel = False,
     test = "//test/syscalls/linux:proc_test",
 )
 
@@ -312,6 +312,7 @@ syscall_test(test = "//test/syscalls/linux:ptrace_test")
 
 syscall_test(
     size = "medium",
+    shard_count = 5,
     test = "//test/syscalls/linux:pty_test",
 )
 
@@ -342,6 +343,7 @@ syscall_test(
 
 syscall_test(
     size = "medium",
+    shard_count = 5,
     test = "//test/syscalls/linux:readv_socket_test",
 )
 
@@ -447,7 +449,6 @@ syscall_test(
 
 syscall_test(
     size = "large",
-    parallel = False,
     shard_count = 10,
     test = "//test/syscalls/linux:socket_inet_loopback_test",
 )
@@ -488,8 +489,6 @@ syscall_test(
 
 syscall_test(
     size = "medium",
-    # Multicast packets can be received by the wrong test if run in parallel.
-    parallel = False,
     test = "//test/syscalls/linux:socket_ipv4_udp_unbound_loopback_test",
 )
 
@@ -528,6 +527,7 @@ syscall_test(
 syscall_test(
     # NOTE(b/116636318): Large sendmsg may stall a long time.
     size = "enormous",
+    shard_count = 5,
     test = "//test/syscalls/linux:socket_unix_dgram_local_test",
 )
 
@@ -546,6 +546,7 @@ syscall_test(
 syscall_test(
     # NOTE(b/116636318): Large sendmsg may stall a long time.
     size = "enormous",
+    shard_count = 5,
     test = "//test/syscalls/linux:socket_unix_seqpacket_local_test",
 )
 
@@ -677,6 +678,7 @@ syscall_test(test = "//test/syscalls/linux:vfork_test")
 
 syscall_test(
     size = "medium",
+    shard_count = 5,
     test = "//test/syscalls/linux:wait_test",
 )
 

test/syscalls/build_defs.bzl

@@ -8,8 +8,7 @@ def syscall_test(
         size = "small",
         use_tmpfs = False,
         add_overlay = False,
-        tags = None,
-        parallel = True):
+        tags = None):
     _syscall_test(
         test = test,
         shard_count = shard_count,
@@ -17,7 +16,6 @@ def syscall_test(
         platform = "native",
         use_tmpfs = False,
         tags = tags,
-        parallel = parallel,
     )
 
     _syscall_test(
@@ -27,7 +25,6 @@ def syscall_test(
         platform = "kvm",
         use_tmpfs = use_tmpfs,
         tags = tags,
-        parallel = parallel,
     )
 
     _syscall_test(
@@ -37,7 +34,6 @@ def syscall_test(
         platform = "ptrace",
         use_tmpfs = use_tmpfs,
         tags = tags,
-        parallel = parallel,
     )
 
     if add_overlay:
@@ -48,7 +44,6 @@ def syscall_test(
             platform = "ptrace",
             use_tmpfs = False,  # overlay is adding a writable tmpfs on top of root.
             tags = tags,
-            parallel = parallel,
             overlay = True,
         )
 
@@ -61,7 +56,6 @@ def syscall_test(
             platform = "ptrace",
             use_tmpfs = use_tmpfs,
             tags = tags,
-            parallel = parallel,
             file_access = "shared",
         )
 
@@ -72,7 +66,6 @@ def _syscall_test(
         platform,
         use_tmpfs,
         tags,
-        parallel,
         file_access = "exclusive",
         overlay = False):
     test_name = test.split(":")[1]
@@ -111,9 +104,6 @@ def _syscall_test(
         "--overlay=" + str(overlay),
     ]
 
-    if parallel:
-        args += ["--parallel=true"]
-
     sh_test(
         srcs = ["syscall_test_runner.sh"],
         name = name,