Re: [PATCH 1/2] writeback: add dirty_background_time per bdi variable

From: Namjae Jeon
Date: Tue Sep 11 2012 - 19:12:33 EST

>> To be frank, no realistic NFS servers will use USB disk as backing
>> storage. So that rational for reducing "initial" delays is weak.
>> Continuous write performance to HDD is much more important. Do you
>> have numbers for that?
> Actually, we use USB HDD and USB Flash devices at NFS server.
> There can be other similar users as well. So it might be useful to
> provide this tuning feature other.
> As default value is zero, it is disabled by default and it should not
> impact normal writeback.
> I will share large file writes test result on NFS client on USB HDD
> with/without tuning with patch.
Hi. Wu.
I share 1GB continous write test result.

-> create a 1000 MB file
For continuous write - create 1 GB file

RecSize WriteSpeed
10485760 10.47MB/sec
1048576 10.35MB/sec
524288 10.48MB/sec
262144 10.48MB/sec
131072 10.52MB/sec
65536 10.56MB/sec
32768 10.64MB/sec
16384 10.31MB/sec
8192 10.52MB/sec
4096 10.45MB/sec

I will update changelog in patch.

Thanks Wu!.
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