Add collect-linux buffersize option

src/Tools/dotnet-trace/CommandLine/Commands/CollectLinuxCommand.cs

@@ -31,6 +31,7 @@ internal sealed record CollectLinuxArgs(
             string ClrEvents,
             string[] PerfEvents,
             string[] Profiles,
+            uint? BufferSizeInMB,
             FileInfo Output,
             TimeSpan Duration,
             string Name,
@@ -175,6 +176,7 @@ public static Command CollectLinuxCommand()
                 CommonOptions.CLREventLevelOption,
                 CommonOptions.CLREventsOption,
                 PerfEventsOption,
+                BufferSizeInMBOption,
                 ProbeOption,
                 CommonOptions.ProfileOption,
                 CommonOptions.OutputPathOption,
@@ -198,6 +200,7 @@ public static Command CollectLinuxCommand()
                     ClrEvents: parseResult.GetValue(CommonOptions.CLREventsOption) ?? string.Empty,
                     PerfEvents: perfEventsValue.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries),
                     Profiles: profilesValue.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries),
+                    BufferSizeInMB: parseResult.GetValue(BufferSizeInMBOption),
                     Output: parseResult.GetValue(CommonOptions.OutputPathOption) ?? new FileInfo(CommonOptions.DefaultTraceName),
                     Duration: parseResult.GetValue(CommonOptions.DurationOption),
                     Name: parseResult.GetValue(CommonOptions.NameOption) ?? string.Empty,
@@ -427,6 +430,14 @@ private byte[] BuildRecordTraceArgs(CollectLinuxArgs args, out string scriptPath
             scriptPath = null;
             List<string> recordTraceArgs = new();
 
+            if (args.BufferSizeInMB.HasValue)
+            {
+                if (args.BufferSizeInMB.Value == 0)
+                {
+                    throw new DiagnosticToolException("Buffer size must be at least 1 MB.");
+                }
+            }
+
             string[] profiles = args.Profiles;
             if (args.Profiles.Length == 0 && args.Providers.Length == 0 && string.IsNullOrEmpty(args.ClrEvents) && args.PerfEvents.Length == 0)
             {
@@ -435,6 +446,13 @@ private byte[] BuildRecordTraceArgs(CollectLinuxArgs args, out string scriptPath
             }
 
             StringBuilder scriptBuilder = new();
+            if (args.BufferSizeInMB.HasValue)
+            {
+                ulong totalBufferSizeBytes = args.BufferSizeInMB.Value * 1024UL * 1024UL;
+                scriptBuilder.AppendLine($"with_buffer_size_bytes({totalBufferSizeBytes});");
+                scriptBuilder.AppendLine();
+            }
+
             List<EventPipeProvider> providerCollection = ProviderUtils.ComputeProviderConfig(args.Providers, args.ClrEvents, args.ClrEventLevel, profiles, true, "collect-linux", Console);
             foreach (EventPipeProvider provider in providerCollection)
             {
@@ -582,6 +600,12 @@ private int OutputHandler(uint type, IntPtr data, UIntPtr dataLen)
                 Description = @"Comma-separated list of perf events (e.g. syscalls:sys_enter_execve,sched:sched_switch)."
             };
 
+        private static readonly Option<uint?> BufferSizeInMBOption =
+            new("--buffersize")
+            {
+                Description = "Requested total size of the event buffers, in megabytes. When omitted, the recorder chooses a default based on the enabled features."
+            };
+
         private static readonly Option<bool> ProbeOption =
             new("--probe")
             {

src/tests/dotnet-trace/CollectLinuxCommandFunctionalTests.cs

@@ -38,6 +38,7 @@ private static CollectLinuxCommandHandler.CollectLinuxArgs TestArgs(
             string clrEvents = "",
             string[] perfEvents = null,
             string[] profile = null,
+            uint? bufferSizeInMB = null,
             FileInfo output = null,
             TimeSpan duration = default,
             string name = "",
@@ -50,6 +51,7 @@ private static CollectLinuxCommandHandler.CollectLinuxArgs TestArgs(
                                                                    clrEvents,
                                                                    perfEvents ?? Array.Empty<string>(),
                                                                    profile ?? Array.Empty<string>(),
+                                                                   bufferSizeInMB,
                                                                    output ?? new FileInfo("trace.nettrace"),
                                                                    duration,
                                                                    name,
@@ -359,6 +361,45 @@ public void CollectLinuxCommand_DoesNotReadKey_WhenInputIsRedirected()
             Assert.True(callbackInvoked);
         }
 
+        [ConditionalFact(nameof(IsCollectLinuxSupported))]
+        public void CollectLinuxCommand_AddsBufferSizeToScript()
+        {
+            string outputPath = Path.Combine(Path.GetTempPath(), $"collect-linux-{Guid.NewGuid():N}.nettrace");
+            string scriptPath = Path.ChangeExtension(outputPath, ".script");
+            MockConsole console = new(200, 30, _outputHelper);
+            var handler = new CollectLinuxCommandHandler(console);
+            handler.RecordTraceInvoker = (cmd, len, cb) => {
+                Assert.Contains(
+                    "with_buffer_size_bytes(268435456);",
+                    File.ReadAllText(scriptPath));
+                return 0;
+            };
+
+            int exitCode = handler.CollectLinux(TestArgs(
+                bufferSizeInMB: 256,
+                output: new FileInfo(outputPath)));
+
+            Assert.Equal((int)ReturnCode.Ok, exitCode);
+        }
+
+        [ConditionalFact(nameof(IsCollectLinuxSupported))]
+        public void CollectLinuxCommand_RejectsZeroBufferSize()
+        {
+            MockConsole console = new(200, 30, _outputHelper);
+            var handler = new CollectLinuxCommandHandler(console);
+            handler.RecordTraceInvoker = (cmd, len, cb) => {
+                Assert.Fail("RecordTrace should not be invoked for an invalid buffer size.");
+                return 0;
+            };
+
+            int exitCode = handler.CollectLinux(TestArgs(bufferSizeInMB: 0));
+
+            Assert.Equal((int)ReturnCode.ArgumentError, exitCode);
+            console.AssertSanitizedLinesEqual(
+                null,
+                FormatException("Buffer size must be at least 1 MB."));
+        }
+
         [ConditionalFact(nameof(IsCollectLinuxSupported))]
         public void CollectLinuxCommand_PrintsStatusOnce_WhenCursorRepositioningUnsupported()
         {