#!/bin/bash # # Here's how to use this: # # This script is used to help find functions that are being traced by function # tracer or function graph tracing that causes the machine to reboot, hang, or # crash. Here's the steps to take. # # First, determine if function tracing is working with a single function: # # (note, if this is a problem with function_graph tracing, then simply # replace "function" with "function_graph" in the following steps). # # # cd /sys/kernel/debug/tracing # # echo schedule > set_ftrace_filter # # echo function > current_tracer # # If this works, then we know that something is being traced that shouldn't be. # # # echo nop > current_tracer # # # cat available_filter_functions > ~/full-file # # ftrace-bisect ~/full-file ~/test-file ~/non-test-file # # cat ~/test-file > set_ftrace_filter # # *** Note *** this will take several minutes. Setting multiple functions is # an O(n^2) operation, and we are dealing with thousands of functions. So go # have coffee, talk with your coworkers, read facebook. And eventually, this # operation will end. # # # echo function > current_tracer # # If it crashes, we know that ~/test-file has a bad function. # # Reboot back to test kernel. # # # cd /sys/kernel/debug/tracing # # mv ~/test-file ~/full-file # # If it didn't crash. # # # echo nop > current_tracer # # mv ~/non-test-file ~/full-file # # Get rid of the other test file from previous run (or save them off somewhere). # # rm -f ~/test-file ~/non-test-file # # And start again: # # # ftrace-bisect ~/full-file ~/test-file ~/non-test-file # # The good thing is, because this cuts the number of functions in ~/test-file # by half, the cat of it into set_ftrace_filter takes half as long each # iteration, so don't talk so much at the water cooler the second time. # # Eventually, if you did this correctly, you will get down to the problem # function, and all we need to do is to notrace it. # # The way to figure out if the problem function is bad, just do: # # # echo > set_ftrace_notrace # # echo > set_ftrace_filter # # echo function > current_tracer # # And if it doesn't crash, we are done. # # If it does crash, do this again (there's more than one problem function) # but you need to echo the problem function(s) into set_ftrace_notrace before # enabling function tracing in the above steps. Or if you can compile the # kernel, annotate the problem functions with "notrace" and start again. # if [ $# -ne 3 ]; then echo 'usage: ftrace-bisect full-file test-file non-test-file' exit fi full=$1 test=$2 nontest=$3 x=`cat $full | wc -l` if [ $x -eq 1 ]; then echo "There's only one function left, must be the bad one" cat $full exit 0 fi let x=$x/2 let y=$x+1 if [ ! -f $full ]; then echo "$full does not exist" exit 1 fi if [ -f $test ]; then echo -n "$test exists, delete it? [y/N]" read a if [ "$a" != "y" -a "$a" != "Y" ]; then exit 1 fi fi if [ -f $nontest ]; then echo -n "$nontest exists, delete it? [y/N]" read a if [ "$a" != "y" -a "$a" != "Y" ]; then exit 1 fi fi sed -ne "1,${x}p" $full > $test sed -ne "$y,\$p" $full > $nontest mmit/net/rds?h=nds-private-remove&id=6e978b22efa1db9f6e71b24440b5f1d93e968ee3'>rds/tcp_stats.c
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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2017-02-03 14:18:39 -0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-02-04 00:11:08 +0100
commit6e978b22efa1db9f6e71b24440b5f1d93e968ee3 (patch)
treec666f7a26b860674848949e39a610222b0723f89 /net/rds/tcp_stats.c
parent3c223c19aea85d3dda1416c187915f4a30b04b1f (diff)
cpufreq: intel_pstate: Disable energy efficiency optimization
Some Kabylake desktop processors may not reach max turbo when running in HWP mode, even if running under sustained 100% utilization. This occurs when the HWP.EPP (Energy Performance Preference) is set to "balance_power" (0x80) -- the default on most systems. It occurs because the platform BIOS may erroneously enable an energy-efficiency setting -- MSR_IA32_POWER_CTL BIT-EE, which is not recommended to be enabled on this SKU. On the failing systems, this BIOS issue was not discovered when the desktop motherboard was tested with Windows, because the BIOS also neglects to provide the ACPI/CPPC table, that Windows requires to enable HWP, and so Windows runs in legacy P-state mode, where this setting has no effect. Linux' intel_pstate driver does not require ACPI/CPPC to enable HWP, and so it runs in HWP mode, exposing this incorrect BIOS configuration. There are several ways to address this problem. First, Linux can also run in legacy P-state mode on this system. As intel_pstate is how Linux enables HWP, booting with "intel_pstate=disable" will run in acpi-cpufreq/ondemand legacy p-state mode. Or second, the "performance" governor can be used with intel_pstate, which will modify HWP.EPP to 0. Or third, starting in 4.10, the /sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference attribute in can be updated from "balance_power" to "performance". Or fourth, apply this patch, which fixes the erroneous setting of MSR_IA32_POWER_CTL BIT_EE on this model, allowing the default configuration to function as designed. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Reviewed-by: Len Brown <len.brown@intel.com> Cc: 4.6+ <stable@vger.kernel.org> # 4.6+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'net/rds/tcp_stats.c')