Re: [Q] is NSFileHandle's writeData method faster than the FSWriteFork?
Re: [Q] is NSFileHandle's writeData method faster than the FSWriteFork?
- Subject: Re: [Q] is NSFileHandle's writeData method faster than the FSWriteFork?
- From: Jens Alfke <email@hidden>
- Date: Fri, 1 Aug 2008 21:14:34 -0700
On 1 Aug '08, at 7:27 PM, JongAm Park wrote:
I measured the performance and found out that the most of the time
were spent with the FSWriteFork() function.
Probably other parts should be streamlined also, but it would impact
significantly if the file write can be faster.
You should sample the export process with both code paths (native FCP
as well as with your plugin). Then you can find how much time each one
takes in file I/O. fs_usage will also tell you how big the writes are
and whether they're cached.
Uncached writes really can make a difference, especially if there's a
lot of memory in use. A cached write will save each written page in
RAM, which often forces an existing page to be evicted to make room;
and if that page is dirty, it has to be written back to disk first.
That can double the number of disk writes.
—Jens_______________________________________________
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