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Re: large scale (audio) file I/O on OS X : help or insight requested
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Re: large scale (audio) file I/O on OS X : help or insight requested

  • Subject: Re: large scale (audio) file I/O on OS X : help or insight requested
  • From: Paul Davis <email@hidden>
  • Date: Thu, 05 Mar 2015 21:50:18 -0600


On Thu, Mar 5, 2015 at 8:48 PM, Hamilton Feltman <email@hidden> wrote:

Ok, that clarifies the issue drastically. One thing to check is possibly something else hitting the disk, like spotlight. Anything else touching the disk at that seekrate, and the bandwidth is destroyed. You can disable spotlight for that drive (System preferences -> Spotlight -> Privacy). If it’s not spotlight, a utility called fseventer will show system wide file access, but it doesn’t look like mavericks is supported yet. But there has got to be a command line util that can watch fsevent. 

we used dtrace to track all file access at both the disk level and hfs+ level. we never saw any patterns of other file access that would explain the slow down.

i'll try the F_RDAHEAD trick tomorrow when i get the mini up and running. sadly, our code *does* assume that we have a reasonable sane OS that will do sensible read-ahead for us, but we've never believed that we were testing a system that didn't do that :) 
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References: 
 >Re: large scale (audio) file I/O on OS X : help or insight requested (From: Hamilton Feltman <email@hidden>)
 >Re: large scale (audio) file I/O on OS X : help or insight requested (From: Paul Davis <email@hidden>)
 >Re: large scale (audio) file I/O on OS X : help or insight requested (From: Hamilton Feltman <email@hidden>)
 >Re: large scale (audio) file I/O on OS X : help or insight requested (From: Paul Davis <email@hidden>)
 >Re: large scale (audio) file I/O on OS X : help or insight requested (From: Hamilton Feltman <email@hidden>)

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