[Pvfs2-developers] concurrent metadata and pvfs2-lsplus improvements

[Rob Ross]

Should we just replace pvfs2-ls with pvfs2-lsplus? -- Rob

On Apr 3, 2008, at 8:07 PM, Phil Carns wrote:
> There are a couple of performance bug fixes in trunk and 2.7 branch  
> now that I thought might be of interest to the list.
>
> The first went in about two weeks ago and fixed a condition variable  
> bug inside of the trove testcontext() function.  There was a race  
> condition where it was possible for operations to complete without  
> waking up the caller, therefore causing the function to sleep longer  
> than it should have.
>
> I don't know how hard it was to trigger in general, but I was able  
> to see it on SMP servers with default sync coalescing and a large  
> number of concurrent metadata modifications.  I was testing it with  
> an artificial benchmark that emulated 10,000 concurrent creates on a  
> server without network traffic, and fixing this bug improved the  
> overall performance of this scenario by a factor of 16.  Hopefully  
> some of this will translate into real world improvement if you have  
> a big concurrent metadata workload.
>
> The second bug fix just went in this week.  The problem was  
> basically some leftover (and very slow) deprecated code in the trove  
> list_attr() function used by readdirplus().  It showed up in the  
> pvfs2-lsplus command line utility, which was supposed to be a much  
> faster version of ls (particularly with -l), but actually ran slower  
> than pvfs2-ls for many cases.
>
> At any rate, this list_attr() problem is fixed now as well.  The  
> result is that it sped up the pvfs2-lsplus by at least a factor of 4  
> for the cases that I was looking at with thousands of files on a  
> single server.  pvfs2-lsplus is definitely a big improvement now if  
> you need a fast way to list files.
>
> -Phil
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