Hi Jeff,

        I just tried the patch you suggested and it didn't make a difference.
The load still spikes as soon as the free space falls below ~10%.


On Fri, 2006-06-30 at 12:47 -0400, Jeff Mahoney wrote:
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> Hans Reiser wrote:
> > Mike Benoit wrote:
> > 
> >> This seems strange, because to me this type of workload would lend
> >> itself to being less fragmented then most workloads. All the box does is
> >> records TV programs, so over the course of 30-60min periods I would
> >> guess 95+% of the writes are sequential. 
> >>
> >> Why would the fragmentation be so bad? Is there a way to tell what the
> >> fragmentation rate is?
> >>
> >> Thanks.
> >>
> >>  
> >>
> > I wonder how the bitmap optimizations that Jeff added handle this usage
> > pattern.  Jeff?
> 
> That's certainly interesting. The bitmap hinting code should skip bitmap
> blocks with fewer blocks that are being asked for. The first zero hint
> patch was never applied to mainline. I have that in my queue as well.
> 
> Try using the attached patch. It directs the block allocator to start
> the search at the first known 0 bit rather than scanning the entire
> block to find it. I'm not sure if will have a meaningful performance
> impact, but it's worth a try.
> 
> - -Jeff
> 
> - --
> Jeff Mahoney
> SUSE Labs
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-- 
Mike Benoit <[EMAIL PROTECTED]>

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