Hi,
I am novice kernel programmer. My name is Dinesh and I am from India. Well last day I was experimenting with blktrace utility benchmarking current file system. I had a strange observation with regarding ext2 and ext3.
With the latest blktrace dated 21-May, the I obtained following logs for ext2 and ext3.
EXT3:
***************************************************************************
Reads Queued: 376, 1,504KiB Writes Queued: 11,419K,
45,679MiB
Read Dispatches: 376, 1,504KiB Write Dispatches: 97,257,
45,679MiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 376, 1,504KiB Writes Completed: 97,257,
45,679MiB
Read Merges: 0, 0KiB Write Merges: 11,316K,
45,264MiB
Read depth: 2 Write depth: 2
IO unplugs: 631 Timer unplugs: 1
Throughput (R/W): 1KiB/s / 57,916KiB/s
EXT2:
****************************************************************************
Reads Queued: 10,840, 43,360KiB Writes Queued: 316,003,
45,723MiB
Read Dispatches: 10,840, 43,360KiB Write Dispatches: 104,976,
45,723MiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 10,840, 43,360KiB Writes Completed: 104,976,
45,723MiB
Read Merges: 0, 0KiB Write Merges: 210,043,
1,622MiB
Read depth: 2 Write depth: 2
IO unplugs: 19,473 Timer unplugs: 2
Throughput (R/W): 60KiB/s / 63,705KiB/s
*****************************************************************************
Even if the I/O queued and dispatched are almost same for both ext2 and ext3, the number of commands queued and dispatched is different for both.
For ext3 Number of writes queued = 11,419 K, writes dispatched = 97,257.
For ext2 Number of writes queued = 316,003, writes dispatched = 104,976.
I am not able to understand why ext3 filesystem is queuing so many I/Os. Please help me to understand this strange behavior.
Any help is highly appreciated.
Please CC to mail id also.
Thanks
Dinesh Kumar Bhaskaran
