Fix clat-percentile accuracy in fio

This fix is to address internal bug#309563824.
As recorded in this bug, fio by default supports
clat percentile values to be calculated accurately upto only
2^(FIO_IO_U_PLAT_GROUP_NR + 5) ns = 14 ms
(with default value of FIO_IO_U_PLAT_GROUP_NR = 29). This change increases it upto 32, to allow
latencies upto 112 ms to be calculated accurately.

perfmetrics/scripts/fio/install_fio.sh

@@ -32,10 +32,17 @@ echo "Installing fio ..."
 sudo apt-get install -y libaio-dev
 
 # We are building fio from source because of the issue: https://github.com/axboe/fio/issues/1668.
+# The sed command below is to address internal bug#309563824. 
+# As recorded in this bug, fio by-default supports 
+# clat percentile values to be calculated accurately upto only 
+# 2^(FIO_IO_U_PLAT_GROUP_NR + 5) ns = 14 ms 
+# (with default value of FIO_IO_U_PLAT_GROUP_NR = 29). This change increases it upto 32, to allow
+# latencies upto 112 ms to be calculated accurately.
 sudo rm -rf "$FIO_SRC_DIR" && \
 git clone https://github.com/axboe/fio.git "$FIO_SRC_DIR" && \
 cd  "$FIO_SRC_DIR" && \
 git checkout fio-3.35 && \
+sed -i 's/define \+FIO_IO_U_PLAT_GROUP_NR \+\([0-9]\+\)/define FIO_IO_U_PLAT_GROUP_NR 32/g' stat.h && \
 ./configure && make && sudo make install
 
 # Now, print the installed fio version for verification