From 6f5dd44f1fb662958e7f648f1efb1683c704c619 Mon Sep 17 00:00:00 2001
From: Bartosz Taudul <wolf.pld@gmail.com>
Date: Thu, 26 Sep 2019 22:55:02 +0200
Subject: [PATCH] Helper for reading data from kernel more efficiently.

---
 extra/systrace/tracy_systrace.c | 36 +++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 extra/systrace/tracy_systrace.c

diff --git a/extra/systrace/tracy_systrace.c b/extra/systrace/tracy_systrace.c
new file mode 100644
index 00000000..3ecc0f4d
--- /dev/null
+++ b/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;
+}