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Date:   Wed, 14 Oct 2020 12:41:39 +0800
From:   Wang Yugui <wangyugui@e16-tech.com>
To:     linux-xfs@vger.kernel.org
Subject: Re: dbench throughput(sync, reflink=0|1) on xfs over hardware throughput
Cc:     wangyugui@e16-tech.com
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Hi,

For xfs sync performance optimization, there is an option 'osyncisdsync'
which is removed in 4.0(man xfs)

the xfs sync performance optimization in linux 5.4.70/5.9.0 is beyond
'osyncisdsync'? When multiple write(sync) at the same time, just some of
them are guaranteed?

Or deduplication(based on reflink=1) help the sync write?
and 'mkfs.xfs -m reflink=0' failed to disable it?

iotop show that 'Actual DISK WRITE:' is NOT over hardware throughput.

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2020/10/14

> Hi,
> 
> #any reply, please Cc: wangyugui@e16-tech.com
> 
> dbench throughput(sync, reflink=0|1) on xfs over hardware
> throughput(6Gb/s=750MB/s).
> 
> Is this a bug of xfs sync?  or some feature of performance optimization?
> 
> we test mkfs.xfs -m reflink=0|1, crc=0|1, still over hardware
> throughput(6Gb/s=750MB/s).
> 
> Disk: TOSHIBA  PX05SMQ040
> This is a 12Gb/s SAS SSD disk, but connect to 6Gb/s SAS HBA,
> so it works with 6Gb/s.
> 
> dbench -s -t 60 -D /xfs 32
> #Throughput 884.406 MB/sec (sync open)
> 
> 
> dbench -s -t 60 -D /xfs 1
> #Throughput 149.172 MB/sec (sync open)
> 
> we test the same disk with ext4 filesystem, 
> the throughput is very close to, but less than the hardware limit.
> 
> dbench -s -t 60 -D /ext4 32
> #Throughput 740.95 MB/sec (sync open)
> 
> dbench -s -t 60 -D /ext4 1
> #Throughput 124.67 MB/sec (sync open)
> 
> linux kernel: 5.4.70, 5.9.0
> 
> Best Regards
> Wang Yugui (wangyugui@e16-tech.com)
> 2020/10/13
>