On Mon, 05 Mar 2007 11:02:43 +0000 Pádraig Brady <[EMAIL PROTECTED]> wrote:
> Andrew Morton wrote: > > I've uploaded to http://userweb.kernel.org/~akpm/pagecache-management/ a > > little tool which permits the management of the pagecache usage of > > arbitrary applications. Effectively it prevents the targetted application > > from using any pagecache at all. > > Cool, Kinda like noca? > http://kernel.umbrella.ro/vm/ yup, same concept. > Though I could easily read your code, > but couldn't immediately figure out what noca was doing. > > I used posix_fadvise in an app I did recently: > http://www.pixelbeat.org/programs/dvd-vr/ > There is a stream_data() func there that does: > > read(src) > write(dst) > posix_fadvise(src) > posix_fadvise(dst) > > for performance I found I needed to do it in that order > so that any readahead done with the read(src) > was not thrown away by the posix_fadvise(src). > In addition to the order, one must be careful > to throw away only what you've actually written. > > I'm not sure your lib gives enough control over this, > as you essentially do: > > posix_fadvise(src) > read(src) > posix_fadvise(dst) > write(dst) That could be so - it's just a demo. But readahead should be OK - I only invalidate from start-of-file up to current-offset-minus-pagesize. So the cache at and ahead of the linear reader is undisturbed. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/