turbostat: Backport 'Drop temperature checks'

The Intel 64 and IA-32 Architectures Software Developer's Manual says
that TjMax is stored in bits 23:16 of MSR_TEMPERATURE TARGET (0x1a2).
That's 8 bits, not 7, so it must be masked with 0xFF rather than 0x7F.

The manual has no mention of which values should be considered valid,
which kind of implies that they all are. Arbitrarily discarding values
outside a specific range is wrong. The upper range check had to be
fixed recently (commit 144b44b1) and the lower range check is just as
wrong. See bug #75071:

https://bugzilla.kernel.org/show_bug.cgi?id=75071

There are many Xeon processor series with TjMax of 70, 71 or 80
degrees Celsius, way below the arbitrary 85 degrees Celsius limit.
There may be other (past or future) models with even lower limits.

So drop this arbitrary check. The only value that would be clearly
invalid is 0. Everything else should be accepted.

After these changes, turbostat is aligned with what the coretemp
driver does.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Len Brown <len.brown@intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[git@lerya.net: Ported to collectd turbostat plugin]
Signed-off-by: Vincent Brillault <git@lerya.net>

diff --git a/src/turbostat.c b/src/turbostat.c
index d62b522..b81eb3c 100644 (file)
--- a/src/turbostat.c
+++ b/src/turbostat.c
@@ -1051,9 +1051,9 @@ set_temperature_target(struct thread_data *t, struct core_data *c, struct pkg_da
        if (get_msr(t->cpu_id, MSR_IA32_TEMPERATURE_TARGET, &msr))
                goto guess;
 
-       target_c_local = (msr >> 16) & 0x7F;
+       target_c_local = (msr >> 16) & 0xFF;
 
-       if (target_c_local < 85 || target_c_local > 127)
+       if (!target_c_local)
                goto guess;
 
        p->tcc_activation_temp = target_c_local;