From 714f4e72b58af0b0036bae45effd2b9d650ac364 Mon Sep 17 00:00:00 2001
From: Nitin Garg <113666283+gargnitingoogle@users.noreply.github.com>
Date: Tue, 21 Nov 2023 09:42:12 +0530
Subject: [PATCH] Fix clat-percentile accuracy in fio (#1503)

* 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.

* address comments
---
 perfmetrics/scripts/fio/install_fio.sh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/perfmetrics/scripts/fio/install_fio.sh b/perfmetrics/scripts/fio/install_fio.sh
index dc4052c9fd..c25c00ed29 100755
--- a/perfmetrics/scripts/fio/install_fio.sh
+++ b/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 = 17.17 seconds. 
+# (with default value of FIO_IO_U_PLAT_GROUP_NR = 29). This change increases it upto 32, to allow
+# latencies upto 137.44s 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-3.36 && \
+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