On Tue, Apr 09, 2013 at 02:01:18PM -0700, Srinivas Pandruvada wrote: > > v2.0 > As suggested by Guenter Roeck, used the previous development in this area > as starting point. The first patch is same as what Guenter Roeck submitted > before except for checkpatch error for strtoul.As per this patch, the following > additional coretemp sysfs entries will be added: > tempX_threshold1 - Reflects value of CPU thermal threshold T0. > tempX_threshold1_triggered > - Reflects status of CPU thermal status register bit 6 > (THERM_STATUS_THRESHOLD0). > tempX_threshold2 - Reflects value of CPU thermal threshold T1. > tempX_threshold2_triggered > - Reflects status of CPU thermal status register bit 8 > (THERM_STATUS_THRESHOLD1). > > > The notification mechanism is implemented for package level by using uevent. > Also a debugfs interface is added to check count of interrupts and worker fn > scheduling. > > > v1.0 > > 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. > > Notification are added only for package level thresholds, to minimize events. Also > interrupts are enabled only when a non tj_max(default) 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.* > > Guenter Roeck (1): > hwmon: (coretemp) Add support for thermal threshold attributes > > Srinivas Pandruvada (3): > x86, mcheck, therm_throt: Process package thresholds > hwmon: (coretemp) : Add notification support > hwmon: (coretemp) : Add debugfs to support thresholds > > Documentation/hwmon/coretemp | 8 + > arch/x86/include/asm/mce.h | 7 + > arch/x86/kernel/cpu/mcheck/therm_throt.c | 63 ++++++- > drivers/hwmon/coretemp.c | 292 +++++++++++++++++++++++++++++-- > 4 files changed, 356 insertions(+), 14 deletions(-) > Rui, can you have a look at this series ? I would like to get some feedback from thermal subsystem supporters if hwmon is really the right place for this. I may be wrong, but it seems to me it would better fit into thermal. Thanks, Guenter _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
