[doc] Added nice to reducing_variance (#1994)

* docs:added nice to reducing_variance

* Added self as contributor

Author: Proxihox

AUTHORS

@@ -56,6 +56,7 @@ Norman Heino <norman.heino@gmail.com>
 Oleksandr Sochka <sasha.sochka@gmail.com>
 Ori Livneh <ori.livneh@gmail.com>
 Paul Redmond <paul.redmond@gmail.com>
+Prithvi Rao <ee22b024@smail.iitm.ac.in>
 Radoslav Yovchev <radoslav.tm@gmail.com>
 Raghu Raja <raghu@enfabrica.net>
 Rainer Orth <ro@cebitec.uni-bielefeld.de>

CONTRIBUTORS

@@ -80,6 +80,7 @@ Ori Livneh <ori.livneh@gmail.com>
 Pascal Leroy <phl@google.com>
 Paul Redmond <paul.redmond@gmail.com>
 Pierre Phaneuf <pphaneuf@google.com>
+Prithvi Rao <ee22b024@smail.iitm.ac.in>
 Radoslav Yovchev <radoslav.tm@gmail.com>
 Raghu Raja <raghu@enfabrica.net>
 Rainer Orth <ro@cebitec.uni-bielefeld.de>

docs/reducing_variance.md

@@ -105,23 +105,28 @@ Linux workstation are:
 
 1. Use the performance governor as [discussed
 above](user_guide#disabling-cpu-frequency-scaling).
-1. Disable processor boosting by:
+2. Disable processor boosting by:
    ```sh
    echo 0 | sudo tee /sys/devices/system/cpu/cpufreq/boost
    ```
    See the Linux kernel's
    [boost.txt](https://www.kernel.org/doc/Documentation/cpu-freq/boost.txt)
    for more information.
-2. Set the benchmark program's task affinity to a fixed cpu.  For example:
+3. Set the benchmark program's task affinity to a fixed cpu.  For example:
    ```sh
    taskset -c 0 ./mybenchmark
    ```
-3. Disabling Hyperthreading/SMT.  This can be done in the Bios or using the
+4. Increase the program's scheduling priority to minimize context switches using `nice` or `chrt`:
+   ```sh
+   sudo nice -n -20 ./mybenchmark
+   sudo chrt -f 80 ./mybenchmark
+   ```
+5. Disabling Hyperthreading/SMT.  This can be done in the Bios or using the
    `/sys` file system (see the LLVM project's [Benchmarking
    tips](https://llvm.org/docs/Benchmarking.html)).
-4. Close other programs that do non-trivial things based on timers, such as
+6. Close other programs that do non-trivial things based on timers, such as
    your web browser, desktop environment, etc.
-5. Reduce the working set of your benchmark to fit within the L1 cache, but
+7. Reduce the working set of your benchmark to fit within the L1 cache, but
    do be aware that this may lead you to optimize for an unrealistic
    situation.