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Re: Speed-optimized file copy
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Re: Speed-optimized file copy


  • Subject: Re: Speed-optimized file copy
  • From: Wim Lewis <email@hidden>
  • Date: Tue, 19 Jul 2011 10:38:11 -0700

On 18 Jul 2011, at 1:25 PM, Stevo Brock wrote:
> The idea is that with 4 concurrent operations executing, the OS is getting fed a lot of disk operation requests such that it can reorder the requests to maximize file system efficiency.  The deployment is OS X 10.6 minimum so we can use any tech available.
>
> What are ways that we could improve the efficiency of this system?

I haven't tested on Darwin, but on some systems you can get a significant efficiency improvement using the aio_* interface (POSIX asynchronous IO). Not only does this let the kernel see multiple outstanding requests and retire them out-of-order, but the particular semantics of aio require less work from the VM system to guarantee correctness. Darwin's different, presumably, but it might be worth looking into.


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