Re: Speed-optimized file copy
Re: Speed-optimized file copy
- Subject: Re: Speed-optimized file copy
- From: email@hidden
- Date: Tue, 19 Jul 2011 19:22:52 -0500
On Tue, 19 Jul 2011 10:38:11 -0700, Wim Lewis wrote:
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.
This is interesting.
I wonder how many simultaneous requests one can make before the
performance improvements (if there are any on Mac OS X) would disappear
when using AIO...
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