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/presubmit_test/pr_perf_test/build.sh

@@ -74,11 +74,18 @@ function install_requirements() {
   # We are building fio from source because of issue: https://github.com/axboe/fio/issues/1640.
   # The fix is not currently released in a package as of 20th Oct, 2023.
   # TODO: install fio via package when release > 3.35 is available.
+  # 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.
   echo Installing fio
   sudo rm -rf "${KOKORO_ARTIFACTS_DIR}/github/fio"
   git clone https://github.com/axboe/fio.git "${KOKORO_ARTIFACTS_DIR}/github/fio"
   cd  "${KOKORO_ARTIFACTS_DIR}/github/fio" && \
   git checkout c5d8ce3fc736210ded83b126c71e3225c7ffd7c9 && \
+  sed -i 's/define \+FIO_IO_U_PLAT_GROUP_NR \+\([0-9]\+\)/define FIO_IO_U_PLAT_GROUP_NR 17/g' stat.h
   ./configure && make && sudo make install
   fio --version
   cd "${KOKORO_ARTIFACTS_DIR}/github/gcsfuse"

perfmetrics/scripts/run_load_test_and_fetch_metrics.sh

@@ -23,10 +23,17 @@ sudo apt-get install libaio-dev
 # We are building fio from source because of issue: https://github.com/axboe/fio/issues/1640.
 # The fix is not currently released in a package as of 20th Oct, 2023.
 # TODO: install fio via package when release > 3.35 is available.
+# 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 "${KOKORO_ARTIFACTS_DIR}/github/fio"
 git clone https://github.com/axboe/fio.git "${KOKORO_ARTIFACTS_DIR}/github/fio"
 cd  "${KOKORO_ARTIFACTS_DIR}/github/fio" && \
 git checkout c5d8ce3fc736210ded83b126c71e3225c7ffd7c9 && \
+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
 
 cd "${KOKORO_ARTIFACTS_DIR}/github/gcsfuse/perfmetrics/scripts"