diff options
| -rw-r--r-- | tools/slowdown/README | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/tools/slowdown/README b/tools/slowdown/README index d953640..90f2b2c 100644 --- a/tools/slowdown/README +++ b/tools/slowdown/README @@ -1,3 +1,11 @@ +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 ------------------------------------ @@ -14,3 +22,32 @@ 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 |