samba performance difference between old and the latest ?

[Jeremy Allison]

On Sat, Sep 07, 2019 at 07:57:24AM +0900, Namjae Jeon wrote:
> 2019-09-07 1:18 GMT+09:00, Jeremy Allison via samba-technical
> <samba-technical at lists.samba.org>:
> > On Fri, Sep 06, 2019 at 11:01:51AM +0900, Namjae Jeon via samba-technical
> > wrote:
> >> Hello,
> >>
> >> I found something strange during measuring performance with samba these
> >> days.
> >> I checked the performance of samba 4.7.6 and 4.10.6.
> >> There seems to be about 20% performance difference between the two
> >> versions.
> >>
> >> Test environment
> >>  1. use iozone and dd utils
> >>  2. share is tmpfs
> >>  3. smb client is kernel cifs client
> >>  4. oplock disable, oplock = no
> >>  4. command : ./iozone -s1g -r4 -e -i 0 -t 1 -b 24m.xls -+u
> >>
> >> with samba 4.7.6
> >> 	Children see throughput for  1 initial writers 	=   11248.48 kB/sec
> >> 	Parent sees throughput for  1 initial writers 	=   11248.28 kB/sec
> >> 	Min throughput per process 			=   11248.48 kB/sec
> >> 	Max throughput per process 			=   11248.48 kB/sec
> >> 	Avg throughput per process 			=   11248.48 kB/sec
> >> 	Min xfer 					= 1048576.00 kB
> >> 	CPU Utilization: Wall time   93.219    CPU time   29.517    CPU
> >> utilization
> >>
> >> with samba 4.10.6
> >> Children see throughput for  1 initial writers 	=    9018.82 kB/sec
> >> 	Parent sees throughput for  1 initial writers 	=    9018.70 kB/sec
> >> 	Min throughput per process 			=    9018.82 kB/sec
> >> 	Max throughput per process 			=    9018.82 kB/sec
> >> 	Avg throughput per process 			=    9018.82 kB/sec
> >> 	Min xfer 					= 1048576.00 kB
> >> 	CPU Utilization: Wall time  116.265    CPU time   33.182    CPU
> >> utilization
> >>
> >>
> >> ================================================================================
> >> ========
> >> dd test result is same with iozone result.
> >>
> >> samba 4.7.6 : 11.6MB/s
> >> samba 4.10.6 : 9.5MB/s
> >>
> >> with samba 4.7.6 :
> >> root at test1234-Samsung-DeskTop-System:/mnt/read# dd if=/dev/zero of=1.txt
> >> bs=4096
> >> count=1024
> >> 1024+0 records in
> >> 1024+0 records out
> >> 4194304 bytes (4.2 MB, 4.0 MiB) copied, 0.360991 s, 11.6 MB/s
> >>
> >> with samba 4.10.6 :
> >> root at test1234-Samsung-DeskTop-System:/mnt/read# dd if=/dev/zero of=1.txt
> >> bs=4096
> >> count=1024
> >> 1024+0 records in
> >> 1024+0 records out
> >> 4194304 bytes (4.2 MB, 4.0 MiB) copied, 0.442567 s, 9.5 MB/s
> >>
> >> Am I missing something? or real issue ?
> >
> > Is this on identical kernel versions ?
> Yes, I compared two versions in the same test environment.

Just checking :-). In that case doing a cachegrind run
on each of the two different versions might show where
the issue is.