sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux; time sync



without discard:

[root@moar tmp]# sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux-3.2.4; time sync

real    0m12.085s
user    0m0.233s
sys     0m2.810s

real    0m0.798s
user    0m0.000s
sys     0m0.023s

real    0m1.170s
user    0m0.037s
sys     0m0.933s

real    0m0.311s
user    0m0.000s
sys     0m0.020s
[root@moar tmp]# ls
linux-3.2.4.tar
[root@moar tmp]# sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux-3.2.4; time sync

real    0m10.555s
user    0m0.230s
sys     0m1.957s

real    0m0.762s
user    0m0.000s
sys     0m0.020s

real    0m1.097s
user    0m0.023s
sys     0m0.907s

real    0m0.299s
user    0m0.000s
sys     0m0.020s
[root@moar tmp]# sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux-3.2.4; time sync

real    0m10.720s
user    0m0.213s
sys     0m1.980s

real    0m0.869s
user    0m0.000s
sys     0m0.023s

real    0m1.148s
user    0m0.023s
sys     0m0.890s

real    0m0.247s
user    0m0.000s
sys     0m0.020s


with discard:
/dev/mapper/home on /home type ext4 (rw,nodiratime,relatime,user_xattr,acl,barrier=1,data=ordered,discard)



[root@moar tmp]# sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux-3.2.4; time sync

real    0m10.568s
user    0m0.237s
sys     0m1.950s

real    0m0.829s
user    0m0.000s
sys     0m0.020s

real    0m1.110s
user    0m0.007s
sys     0m0.910s

real    0m12.236s
user    0m0.000s
sys     0m0.023s
[root@moar tmp]# sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux-3.2.4; time sync

real    0m9.902s
user    0m0.173s
sys     0m1.990s

real    0m0.861s
user    0m0.000s
sys     0m0.027s

real    0m1.143s
user    0m0.030s
sys     0m0.933s

real    0m12.148s
user    0m0.000s
sys     0m0.017s
[root@moar tmp]# sync; echo 3 > /proc/sys/vm/drop_caches; time tar xf linux-3.2.4.tar; time sync; time rm -rf linux-3.2.4; time sync

real    0m10.341s
user    0m0.187s
sys     0m1.983s

real    0m0.828s
user    0m0.000s
sys     0m0.020s

real    0m1.182s
user    0m0.033s
sys     0m0.930s

real    0m12.189s
user    0m0.000s
sys     0m0.017s
[root@moar tmp]#