Re: [rdiff-backup-users] Severe performance degradation

[Jakob Unterwurzacher]

Am 22.12.2010 15:02, schrieb Maarten J H van den Berg:
> On 12/21/10 18:51, Jakob Unterwurzacher wrote:
> 
>>
>> What about the kernel version? Probably barriers are now working as they
>> should and you pay the price for that. dpkg package management had huge
>> performance regressions due to this AFAIR.
> 
> Googled a bit on that but I'm left confused: are you talking about
> memory barriers, ext4 barriers, or some other type ?

I meant hard-disk write barriers as in http://lwn.net/Articles/283161/ ,
but, as the problem seems to be CIFS I think we can forget about iostat.
The CIFS client is built into the kernel, if you want to get rid of the
rsync stage I'd try the older kernel or experiment with CIFS mount
options, ( rsize=130048 is recommended often).

Regards,
Jakob

> 
>> Other than that, I'd try to find out where rdiff-backup is spending all
>> the the time. What does
>> iostat -dx 1
>> in the %utils column say while an incremental is running?
>> You could even fire up sysprof to see what it is waiting for.
> 
> We did monitor that a couple of weeks back. I do not have numbers
> readily available now but we did not find a specific reason I believe.
> 
> For now I'm going to probably work around it by making the process a
> two-phase one: first step rsync, second step rdiff-backup...
> I may still do repaet tests with iostat later, if only to find out what
> is causing this...
> 
> Cheers!
> Maarten
> 
>> Regards,
>> Jakob
>>
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> 
> 
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