Messages in this thread | | | Date | Wed, 12 Sep 2012 15:04:29 +0900 | Subject | Re: [PATCH 1/2] writeback: add dirty_background_time per bdi variable | From | Namjae Jeon <> |
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2012/9/12, Namjae Jeon <linkinjeon@gmail.com>: > 2012/9/12, Fengguang Wu <fengguang.wu@intel.com>: >> On Wed, Sep 12, 2012 at 08:12:40AM +0900, Namjae Jeon wrote: >>> >> >>> >> 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! What's the server side setting > I missed server side setting.. I set dirty_background_centisecs to 1 sec. >> and can you give a comparison of different background writeback >> thresholds? > Okay, I will measure peformance per setting value of > dirty_background_centisecs in nfs server. > > This is this patch's >> target use cases, after all. > Sure. > Thanks.
Hi. Wu.
I shared write performance result as your suggestion.
----------------------------------------------------------- dirty_background_centisecs = 0, default value ----------------------------------------------------------- [NFS Server] $ cat /sys/block/sda/bdi/dirty_background_centisecs 0 [NFS Client] $ ./performancetest_arm 1GB_file WRT_SZ = 1000 MB RecSize WriteSpeed 10485760 8.44MB/sec 1048576 8.48MB/sec 524288 8.37MB/sec 262144 8.16MB/sec 131072 8.48MB/sec 65536 8.38MB/sec 32768 8.65MB/sec 16384 8.27MB/sec 8192 8.52MB/sec 4096 8.20MB/sec
----------------------------------------------------------- dirty_background_centisecs = 300, i.e. 3 seconds ----------------------------------------------------------- [NFS Server] $ echo 300 > /sys/block/sda/bdi/dirty_background_centisecs $ cat /sys/block/sda/bdi/dirty_background_centisecs 300 [NFS Client] $ ./performancetest_arm 1GB_file RecSize WriteSpeed 10485760 8.60MB/sec 1048576 8.87MB/sec 524288 8.42MB/sec 262144 8.51MB/sec 131072 8.81MB/sec 65536 9.09MB/sec 32768 9.00MB/sec 16384 8.80MB/sec 8192 8.70MB/sec 4096 8.63MB/sec
----------------------------------------------------------- dirty_background_centisecs = 200, i.e. 2 seconds ----------------------------------------------------------- [NFS Server] $ echo 200 > /sys/block/sda/bdi/dirty_background_centisecs $ cat /sys/block/sda/bdi/dirty_background_centisecs 200 [NFS Client] $ ./performancetest_arm 1GB_file RecSize WriteSpeed 10485760 9.30MB/sec 1048576 9.31MB/sec 524288 9.84MB/sec 262144 9.52MB/sec 131072 9.42MB/sec 65536 9.76MB/sec 32768 9.57MB/sec 16384 9.39MB/sec 8192 9.40MB/sec 4096 9.80MB/sec
----------------------------------------------------------- dirty_background_centisecs = 100, i.e. 1 second ----------------------------------------------------------- [NFS Server] $ echo 100 > /sys/block/sda/bdi/dirty_background_centisecs $ cat /sys/block/sda/bdi/dirty_background_centisecs 100 [NFS Client] $ ./performancetest_arm 1GB_file RecSize WriteSpeed 10485760 10.27MB/sec 1048576 10.34MB/sec 524288 10.47MB/sec 262144 10.62MB/sec 131072 10.55MB/sec 65536 10.53MB/sec 32768 10.54MB/sec 16384 10.43MB/sec 8192 10.50MB/sec 4096 10.35MB/sec
I will update simple table for this result in changelog in patch.
Thanks.
>> >> Thanks, >> Fengguang >> >
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