On 7/6/07, Alan Cox <alan@xxxxxxxxxx> wrote:
On Fri, Jul 06, 2007 at 04:55:47PM -0400, Colin Walters wrote: > Possibly, but I think the biggest speedup by far is the disk > caching/reorganization that both Windows and OS X do: > http://www.kernelthread.com/mac/apme/optimizations/ > > At this rate though, we might all be using solid state drives before the > kernel developers stop pointing at userspace as the problem and > implement it for Linux. We already lay stuff out very carefully and precache. Unfortunately most of the mess *is* userspace and some of the userspace authors are in complete denial. Just profile the number of file opens of different files done in a gnome startup and when you've finished laughing you can weep. Years ago I sent the gnome team a library that could load and linearlly map the entire theme in about 3 syscalls coming out nicely on disk. They never used it. That isn't to say the kernel is perfect and there is a ton of optimising work still going on, different scheduling algorithms and the like but most of the slowness is from user space - some from tools, some from combinations of tools and kernel (eg linker and paging patterns) and a lot of it from sheer stupid clueless design of applications and especially of GUI libraries.
Speaking from my many days as a performance analyst, Pfeifer's first rule of performance says "The only good I/O is one you don't do". I'll second Alan here. The OS can mitigate the effects of I/O but userspace has the onus to be reasonable. darrell -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
