[Samba] Slow on one client Win7 program

[Huibert van Andel]

> Got one program that is running very, very slow on version 3.6.8.
> Using SMB2, logging level 3 I saw a lot of these:
>
> [2012/09/24 23:44:43.824970,  3] smbd/smb2_read.c:356(smb2_read_complete)
>   smbd_smb2_read: fnum=[8523/filename] length=2 offset=1656 read=2
> [2012/09/24 23:44:43.825499,  3] lib/util.c:1498(fcntl_getlock)
>   fcntl_getlock: fd 34 is returned info 2 pid 0
>
> Seems the files are read in chunks of 2 bytes a call.
> Most of the files the program is reading are a few Mb,
> so why is it only reading 2 bytes at a time?
>
> In ver 3.6.7 I made a few tests also, and it does matter what you choose
> for locking, e.g.:
>
>         kernel oplocks = no
>         oplocks = no
>         level2 oplocks = yes
>
> Some tests worked better (e.g. no locks at all), some not, though with 
> 3.6.8 none provides speed.
> Anyway 3.6.7 had other bugs and was unusable.
> Other programs seem not to be affected (poss. they don't use smb2?).
>
Another few tests does make a difference:
         kernel oplocks = no
         oplocks = yes
         level2 oplocks = yes

Output e.g.:
[2012/09/25 08:17:39.042639,  3] smbd/smb2_read.c:356(smb2_read_complete)
   smbd_smb2_read: fnum=[4824/filename] length=65536 offset=4030464 
read=65536
[2012/09/25 08:17:39.046235,  3] smbd/smb2_read.c:356(smb2_read_complete)
   smbd_smb2_read: fnum=[4824/filename] length=65536 offset=4096000 
read=65536
[2012/09/25 08:17:39.050502,  3] smbd/smb2_read.c:356(smb2_read_complete)
   smbd_smb2_read: fnum=[4824/filename] length=32768 offset=4161536 
read=32768


Seems oplocks = yes is fairly stable to give large reads and speed.
But why is this?

-Huibert.