This is clear that there is reluctance in adding thresholds in coretemp sysfs, during previous attempts. Proably because of lake of use cases. But this time use case may be more compelling. We have many small form factor devices like ultrabooks, slate PCs in the market. Unfortunately these devices reach maximum temperature with relatively less workloads, causing BIOS to do thermal throttling. There are real performance issues due to aggressive BIOS action to control thermals and also thermal breakdown in some cases. Even the most expensive laptops, don't have correct ACPI thermal configuration, so that kernel thermal driver can act. In some case even the trip point is higher than critical temperature setting. Intel has developed several drivers, which can be used to cool the system very efficiently. They include RAPL based cooling driver, Powerclamp driver and P state driver. To utilize these cooling device a closed loop user mode program is required, which will utilize these method and dynamically compensate for high CPU temperatures, without relying on any configuration data. One such solution is developed is "Linux thermal daemon". More details can be obtained from "https://github.com/01org/thermal_daemon/blob/master/ThermalDaemon_Introduction.pdf";. This daemon polls for cpu temperature and apply compensation once the CPU reach target temperature. This polling can be mostly avoided, by getting notification for the temperature, where it needs to wake up and get ready for apply compensation. In most of the normal use cases, there may not be any threshold events. So very minimal number of user space notification for thermal thresholds. This patch adds two entries to coretemp sysfs. tempX_notify_threshold_1 tempX_notify_threshold_2 These two settings acts on "Package level", not on core level. So it will only appear if there is support for package temperature. Many of recent Intel processors, support package temperatures When any valid value is written to these files, it will directly set corresponding CPU MSR, in the corresponding package and read back directly from MSR. Since package MSR, affects all cores in package, setting will be applicable to all CPU's in the package minimizing read, writes and notifications. Also package threshold interrupts are enabled only when, a non zero value is written to thresholds. Once thresholds are violated, it uses a rate control of 5 seconds, reducing the number of interrupts, when temperature is hanging around trip point. Using the sticky log bit, it sends kboject uevent change notification for corresponding package sysfs. Once the thermal daemon receives notification, it can change to new threshold or act immediately to reduce CPU temperature. Srinivas Pandruvada (4): x86, mcheck, therm_throt: Process package thresholds hwmon: (coretemp) Add threshold support hwmon: (coretemp) : Add notification support drivers/hwmon/coretemp : Debug fs interface arch/x86/include/asm/mce.h | 7 + arch/x86/kernel/cpu/mcheck/therm_throt.c | 50 ++++- drivers/hwmon/coretemp.c | 319 +++++++++++++++++++++++++++++-- 3 files changed, 361 insertions(+), 15 deletions(-) -- 1.7.11.7 _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
