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What is slowdown
----------------
slowdown is a shared library implementing libc read(2) and write(3)
with a configurable delay meant for testing programs behaviour when
the disk behaves differently than normal.
How to build and install slowdown.so
------------------------------------
If this directory doesn't contain the file 'configure', run
autoreconf -ivf
before doing
./configure
make install
You will need the GNU auto-tools (Autoconf, Automake, Libool).
See INSTALL for more general information about building and
installing.
How to use slowdown
-------------------
$ # slowdown.so not loaded, for reference
$ dd if=/dev/zero of=/dev/null bs=1 count=100
100+0 records in
100+0 records out
100 bytes (100 B) copied, 0.000269866 s, 371 kB/s
$ # slowdown.so loaded but not configured to delay on purpose
$ LD_PRELOAD=~/usr/lib/libslowdown.so dd if=/dev/zero of=/dev/null bs=1 count=100
100+0 records in
100+0 records out
100 bytes (100 B) copied, 0.0265673 s, 3.8 kB/s
# slowdown.so delaying writes with 1ms
$ LD_PRELOAD=~/usr/lib/libslowdown.so SLOWDOWN_WRITE_DELAY_MS=1 dd if=/dev/zero of=/dev/null bs=1 count=100
100+0 records in
100+0 records out
100 bytes (100 B) copied, 0.127009 s, 0.8 kB/s
$
# slowdown.so delaying both reads and writes with 1ms each
$ LD_PRELOAD=~/usr/lib/libslowdown.so SLOWDOWN_READ_DELAY_MS=1 SLOWDOWN_WRITE_DELAY_MS=1 dd if=/dev/zero of=/dev/null bs=1 count=100
100+0 records in
100+0 records out
100 bytes (100 B) copied, 0.227234 s, 0.4 kB/s
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