This patch was originally written by Bernard Blackham, and modified by
Peter Chubb.
From 0d755af2f5bef22432da71f2fe0a9dce7d2882cd Mon Sep 17 00:00:00 2001
From: Bernard Blackham <bernard.black...@nicta.com.au>
Date: Fri, 24 Jul 2009 13:38:03 +1000
Subject: Disable line-based log buffering.
There's no real reason for line-based buffering in log file output.
If block buffering with a decent sized buffer is used, it can speed
qemu up for -d all or -d exec significantly.
The only thing you lose is that the last up to 4k of log output may be lost if
qemu crashes.
Signed-off-by: Peter Chubb <peter.ch...@nicta.com.au>
Signed-off-by: Hans Jang <hsj...@ok-labs.com>
Signed-off-by: Bernard Blackham <bernard.black...@nicta.com.au>
---
exec.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
Index: qemu-working/exec.c
===================================================================
--- qemu-working.orig/exec.c 2011-09-29 09:03:35.866233828 +1000
+++ qemu-working/exec.c 2011-09-29 12:40:56.668973550 +1000
@@ -1594,29 +1594,28 @@ void cpu_single_step(CPUState *env, int
/* enable or disable low levels log */
void cpu_set_log(int log_flags)
{
loglevel = log_flags;
if (loglevel && !logfile) {
logfile = fopen(logfilename, log_append ? "a" : "w");
if (!logfile) {
perror(logfilename);
_exit(1);
}
+
+/* Don't use line-based buffering: it hurts -d exec */
#if !defined(CONFIG_SOFTMMU)
/* must avoid mmap() usage of glibc by setting a buffer "by hand" */
{
static char logfile_buf[4096];
- setvbuf(logfile, logfile_buf, _IOLBF, sizeof(logfile_buf));
+ setvbuf(logfile, logfile_buf, _IOFBF, sizeof(logfile_buf));
}
-#elif !defined(_WIN32)
- /* Win32 doesn't support line-buffering and requires size >= 2 */
- setvbuf(logfile, NULL, _IOLBF, 0);
#endif
log_append = 1;
}
if (!loglevel && logfile) {
fclose(logfile);
logfile = NULL;
}
}
void cpu_set_log_filename(const char *filename)
--
Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au
http://www.ertos.nicta.com.au ERTOS within National ICT Australia
