Re: Disk streaming library
Re: Disk streaming library
- Subject: Re: Disk streaming library
- From: Paul Davis <email@hidden>
- Date: Thu, 28 Jun 2012 10:54:12 -0400
On Thu, Jun 28, 2012 at 10:41 AM, Philippe Wicker
<email@hidden> wrote:
Hello,
We are currently investigating different solutions to add a disk streaming engine to some of our products. Along with the development of a proprietary solution we're also looking for third party sources. Does anyone knows about a library - including commercial one - that provide a high performance disk streaming engine?
this question is, well, a bit *undefined*.
what do i mean? well lets consider the famous Giga pre-reading behaviour that was the subject of a patent for a while. any unix filesystem of the last 30 years has the same behaviour! if you read N bytes from a given location in the file, the OS will actually read N+M bytes and cache the extra M bytes in memory (the unix buffer cache). the value of N and M are configurable, naturally (though they are unfortunately constant across all files on the filesystem, at least). this behaviour applies even to apple's rather weak unix filesystems. but wait, can't you do better that the OS by rolling your own? say, by opening the file in "direct" mode such that the buffer cache is not used, and then doing intelligent caching in an application/data-specific way?
well, good luck with that. Oracle certainly pulls this off with their databases, but there have been many, many studies where people have tried to do better than the buffer cache and discovered that in real world scenarios, they can't. if you were to accept that to be the end of the story (it probably isn't), then on OS X at least, you wouldn't plan on using any "disk streaming engine" at all - you'd just do regular system calls to read/write and let the OS take care of the rest.
to get any kind of an answer to this question, i suspect you need to describe in more detail what you mean by "a high performance disk streaming solution".
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