Re: CONFIG_IOSCHED_CFQ

[Jens Axboe]

On Sun, Oct 26 2003, ahuisman wrote:
> wuuk:/boot# diff config-2.6.0-test8-mm1 config-2.6.0-test9
> 33d32
> < CONFIG_IOSCHED_CFQ=y
> 87,91d85
> < # CONFIG_X86_4G is not set
> < # CONFIG_X86_SWITCH_PAGETABLES is not set
> < # CONFIG_X86_4G_VM_LAYOUT is not set
> < # CONFIG_X86_UACCESS_INDIRECT is not set
> < # CONFIG_X86_HIGH_ENTRY is not set
> 111d104
> < CONFIG_BOOT_IOREMAP=y
> 257d249
> < # CONFIG_BLK_DEV_SGIIOC4 is not set
> 302a295
> > # CONFIG_SCSI_SATA is not set
> 483d475
> < # CONFIG_NET_POLL_CONTROLLER is not set
> 
> Conclusion:
> 
> CONFIG_IOSCHED_CFQ is removed from 2.6.0-test9
> 
> Questions:
> 
> Am i right with my conclusion ?
> Is this the reason for the loss of performance ?

No you are not correct, must be caused by something else. Just building
CFQ into the kernel doesn't enable it, you need to boot with
elevator=cfq for that to happen. So whether CONFIG_IOSCHED_CFQ is set or
not cannot make a difference by itself.

The performance difference must be caused by some other change between
test8-mm1 and -test9.

-- 
Jens Axboe

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