iostat and fusefs

[Marat N.Afanasyev]

hello!

I've accidently ran iostat while write to fuse filesystem was in 
progress and was shocked when I've seen that, according to iostat, each 
and any write op to fuse fs leads to one read op. i.e. if I have ~100 
write op/s to fuse then I have exatcly ~100 read op/s from the same 
fuse. Is this a bug in iostat or in fuse?

da2: <SanDisk Cruzer Blade 1.00> Removable Direct Access SPC-4 SCSI device
# mount.exfat /dev/da2s1 /mnt/1
FUSE exfat 1.2.4

# dd if=/dev/zero of=/mnt/1/test1280m.fil bs=1m count=1280
^C179+0 records in
178+0 records out
186646528 bytes transferred in 29.778425 secs (6267844 bytes/sec)

# iostat -xzdw10 da2
                         extended device statistics
device       r/s     w/s     kr/s     kw/s  ms/r  ms/w  ms/o  ms/t qlen 
%b
da2           79      79   5068.7   5075.1     3    11     0     7    1  78
                         extended device statistics
device       r/s     w/s     kr/s     kw/s  ms/r  ms/w  ms/o  ms/t qlen 
%b
da2           99      99   6373.4   6392.5     3    11     0     7    0  95
                         extended device statistics
device       r/s     w/s     kr/s     kw/s  ms/r  ms/w  ms/o  ms/t qlen 
%b
da2           95      95   6118.5   6092.9     3    11     0     7    2  95
                         extended device statistics
device       r/s     w/s     kr/s     kw/s  ms/r  ms/w  ms/o  ms/t qlen 
%b
da2           12      12    793.6    793.6     3    14     0     8    0  15

the same can be seen if I use ntfs-3g

no other app is using da2.

-- 
SY, Marat

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 3805 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20170303/058418a4/attachment.bin>