Tested the flusher slightly

[OGAWA Hirofumi]

Daniel Phillips <daniel.raymond.phillips at gmail.com> writes:

>> And FLUSH command makes slower slightly. blocksize 512 makes slower, and
>> increase cpu systime, because probably buffer_head overhead, especially
>> sort of buffer_head (perf says buffer_index_cmp() is top cpu user).
>
> The performance results for this load seem more than satisfactory. The
> superblock commit strategy shows up a only a small part of the cost
> for this load, unsurprisingly, but is probably a much bigger part of
> some other loads, for example a series of small writes, each followed
> by sync.

I was forgetting to measure blockdev (this would be basically best for
this load).

[blockdev]
4294967296 bytes (4.3 GB) copied, 63.138 s, 68.0 MB/s

real	1m3.346s
user	0m0.280s
sys	0m5.484s


tux3 is now 67.2 MB/s, I feel this path can be optimize more (we have
overhead of metadata though, but...). Well, anyway, above one would be
one of goals.

[To measure blockdev, I have to do some sort of tricky way. Because
blockdev seems to initialize the blocksize for each initial open.

      # sleep 3600 < /dev/sdb2 &
      # blockdev --setbsz 4096 /dev/sdb2
      # time dd if=/dev/zero of=/dev/sdb2 bs=4K count=1M
]
-- 
OGAWA Hirofumi <hirofumi at mail.parknet.co.jp>