Hello,
I try to analyze the lock contention in the linux FS, so I enable
lockstats in the kernel. But I have some troubles to understand the
result in lockstats.
When I read 4GB data randomly from a file on a ramdisk with 8 threads
(I have 8 cores), and it takes 21 seconds.
The most contended lock is
class name con-bounces contentions
waittime-min waittime-max
waittime-total acq-bounces acquisitions holdtime-min
holdtime-max holdtime-total
&(&mapping->tree_lock)->rlock 104380 104615 0
0 61705.23 169228 2862470
0 0 1010557.22
&(&zone->lru_lock)->rlock 1233 1245
0 0 2632.71 21834
255752 0 3.86 402904.1
xtime_lock 722 731
0 0 1916.15
1342 2901 0 0
4812.51
What is unit of the waittime? in nanoseconds? I look into the code of
x86, and it seems the clock time the code reads is nanoseconds. But if
it's in nanoseconds, the wait time of mapping->tree_lock is very
short, only 62us in total?
Also, the result shows that there are 104615 contentions out of
2862470 acquisitions. I guess it's not very highly contended.
Thanks,
Da
_______________________________________________
Kernelnewbies mailing list
[email protected]
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
