On Friday 26 January 2007 19:23, Bill Davidsen wrote: > Denis Vlasenko wrote: > > On Thursday 25 January 2007 21:45, Michael Tokarev wrote: > >> Phillip Susi wrote: > >>> Denis Vlasenko wrote: > >>>> You mean "You can use aio_write" ? > >>> Exactly. You generally don't use O_DIRECT without aio. Combining the > >>> two is what gives the big win. > >> Well, it's not only aio. Multithreaded I/O also helps alot -- all this, > >> say, to utilize a raid array with many spindles. > >> > >> But even single-threaded I/O but in large quantities benefits from O_DIRECT > >> significantly, and I pointed this out before. > > > > Which shouldn't be true. There is no fundamental reason why > > ordinary writes should be slower than O_DIRECT. > > > Other than the copy to buffer taking CPU and memory resources.
It is not required by any standard that I know. Kernel can be smarter and avoid that if it can. -- vda - 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/
