Helper for reading data from kernel more efficiently.

extra/systrace/tracy_systrace.c

@@ -0,0 +1,36 @@
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+enum { BufSize = 64*1024 };
+
+int main()
+{
+    char buf[BufSize];
+
+    int kernelFd = open( "/sys/kernel/debug/tracing/trace_pipe", O_RDONLY );
+    if( kernelFd == -1 ) return -1;
+
+    struct pollfd pfd;
+    pfd.fd = kernelFd;
+    pfd.events = POLLIN | POLLERR;
+
+    struct timespec sleepTime;
+    sleepTime.tv_sec = 0;
+    sleepTime.tv_nsec = 1000 * 1000 * 10;
+
+    for(;;)
+    {
+        while( poll( &pfd, 1, 0 ) <= 0 ) nanosleep( &sleepTime, NULL );
+        const int rd = read( kernelFd, buf, BufSize );
+        if( rd <= 0 ) break;
+        write( STDOUT_FILENO, buf, rd );
+    }
+
+    close( kernelFd );
+    return 0;
+}