Re: O_SYNC and Oracle

From: Van Okamura (vokamura@us.oracle.com)
Date: Tue May 16 2000 - 13:44:50 EST


"Jeff V. Merkey" wrote:

> For O_SYNC writes, I am assuming you will be using you the cache in
> Oracle, and that the O_SYNC case will be used flushing commits. What
> frequecy of writes vs. reads do you normally exhibit, and what
> percentage of writes will use the O_SYNC semantic. In my earlier
> dialogue with Alan, the idea came up to call fsync() (which flushes the
> cache) after any calls to write() with O_SYNC set in the file handle. I
> think it would be nice to provide a something less coarse than:
>
> write();
> fsync();
>
> Saying performance is critical is cool, but what would you consider
> would be the best semantic to provide this behavior in a performant
> manner that would allow Oracle to get best case performance?

Well, Redhat Enterprise Edition implements features like raw i/o,
vectored i/o, and 64-bit i/o that improve performance. You could look
at those interfaces for more details.

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