Re: [PATCH] Add ext3 data=guarded mode

[Mike Galbraith <efault@gmx.de>]

On Sun, 2009-04-19 at 11:54 +0530, Amit Shah wrote:
> On (Sat) Apr 18 2009 [09:28:21], Mike Galbraith wrote:

> > Probably because you're swapping heavily, and that is perturbing your
> 
> The variance only affects the 4k test; the other times more or less
> remain the same.

My box disagrees.

(bumps ulimits to test 4BG... OS+swap live on sdb btw)

./test-file-zero-alloc-speed 4 /dev/sdf3 /media/root ext3 rw,_netdev,noatime,data=foo,acl,user_xattr

foo=guarded
4k   225  141   80  142  361
8k    74   96  362   78   84
mm    55   57   57   57   57

foo=writeback
4k   179  264  187  125   93
8k    94  161   73  334   84
mm    57   58   57   56   57

foo=ordered
4k    81   74   76   80   75
8k    77   76  224   79   79 
mm    59   56   60   58   59

foo=journal
4k    95  297   69   83  420
8k    73  139  158   80   78
mm    57   58   56   59   56

./test-file-zero-alloc-speed 2 /dev/sdf3 /media/root ext3 rw,_netdev,noatime,data=foo,acl,user_xattr

foo=guarded
4k    28   27   27   28   28
8k    28   27   27   28   27

foo=writeback
4k    27   27   27   27   27
8k    28   28   27   27   28

All journal modes seem subject to bad throughput under heavy pressure,
though data=ordered seems much less likely to suffer for some reason.
Major difference _seems_ to be that write()+largefile induces very much
swap activity.

	-Mike