Re: [RFT] major libata update

[Tejun Heo <htejun@gmail.com>]

Ric Wheeler wrote:
> 
> Mark Lord wrote:
> 
>> Tejun Heo wrote:
>>
>>> ..
>>> Right.  Also, we need to snoop some passthrough commands and 
>>> revalidate/reconfigure when configuration is explicitly changed.
>>
>>
>> Once the sysfs attr's actually work, I'll probably re-do my hdparm
>> stuff to detect use them when available, avoiding the need for libata
>> to snoop passthrough commands.  But Jeff may (or not) want to snoop 
>> anyway.
>>
>> As a workaround for now, Ric is using the ugly hack attached here.
>>
>> Cheers
> 
> 
> With this patch, I can get the write cache to change properly, but I 
> still see rates that are "too fast" until I disable the queuing as 
> well.  I think that the barriers are supposed to work with NCQ enabled, 
> but might there be a trace of the old "disable" barrier support if 
> queuing is on left somewhere?

I think the easiest way to verify basic things are working is by booting 
the machine with write cache enabled.

> Also, disabling the queue via setting 
> /sys/class/scsi_disk/4\:0\:0\:0/device/queue_depth does not seem to take 
> effect unless I unmount the file system & remount.  I will  poke around 
> to see if reiserfs is disabling with queuing enabled & only reenables on 
> a fresh mount...

I don't think you're supposed to change cache setting underneath a live FS.

-- 
tejun