On Fri, 12 Jan 2007 15:35:09 -0700 Erik Andersen <[EMAIL PROTECTED]> wrote:
> On Fri Jan 12, 2007 at 05:09:09PM -0500, Linus Torvalds wrote: > > I suspect a lot of people actually have other reasons to avoid caches. > > > > For example, the reason to do O_DIRECT may well not be that you want to > > avoid caching per se, but simply because you want to limit page cache > > activity. In which case O_DIRECT "works", but it's really the wrong thing > > to do. We could export other ways to do what people ACTUALLY want, that > > doesn't have the downsides. > > I was rather fond of the old O_STREAMING patch by Robert Love, That was an akpmpatch whcih I did for the Digeo kernel. Robert picked it up to dehackify it and get it into mainline, but we ended up deciding that posix_fadvise() was the way to go because it's standards-based. It's a bit more work in the app to use posix_fadvise() well. But the results will be better. The app should also use sync_file_range() intelligently to control its pagecache use. The problem with all of these things is that the application needs to be changed, and people often cannot do that. If we want a general way of stopping particular apps from swamping pagecache then it'd really need to be an externally-imposed thing - probably via additional accounting and a new rlimit. - 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/