diff mbox

[1/7] tools/power turbostat: bugfix: GFXMHz column not changing

Message ID 22048c5485503749754b3b5daf9d99ef89fcacdc.1492041840.git.len.brown@intel.com (mailing list archive)
State Mainlined
Delegated to: Rafael Wysocki
Headers show

Commit Message

Len Brown April 13, 2017, 12:08 a.m. UTC 
From: Len Brown <len.brown@intel.com>

turbostat displays a GFXMHz column, which comes from reading
/sys/class/graphics/fb0/device/drm/card0/gt_cur_freq_mhz

But GFXMHz was not changing, even when a manual
cat /sys/class/graphics/fb0/device/drm/card0/gt_cur_freq_mhz
showed a new value.

It turns out that a rewind() on the open file is not sufficient,
fflush() (or a close/open) is needed to read fresh values.

Reported-by: Yaroslav Isakov <yaroslav.isakov@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
 tools/power/x86/turbostat/turbostat.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 828dccd3f01e..d7fb6bcb2744 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -2485,8 +2485,10 @@  int snapshot_gfx_mhz(void)
 
 	if (fp == NULL)
 		fp = fopen_or_die("/sys/class/graphics/fb0/device/drm/card0/gt_cur_freq_mhz", "r");
-	else
+	else {
 		rewind(fp);
+		fflush(fp);
+	}
 
 	retval = fscanf(fp, "%d", &gfx_cur_mhz);
 	if (retval != 1)